Will a mid 1960s 727 tailpiece bolt onto a mid 1970s 727?

Gerald Morris

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Greetings My Wise Elder Moparians!

I'm starting to figure out the most cost effective path to upgrading a worn 383/727 to a rebuilt 400 with the 727 meant to run with it. Without getting Down in the Dirt with these machines, yet, I wonder if the tail piece from the older, 1965/66 transmission will bolt onto the 1977 trans. If so, that likely will be the path I take to upgrading the drive train. I want to get this good old motor and tranny out NOW, before heat and city traffic destroy it.

I have 2 other forged crank shafts to pick from for the stroke on a B block, BUT, IFF the rotating assembly is in good enough shape to run it, I'll happily use the cast iron crank with the external balancing.

Now is The Time! to start this project. I'm going to look at Hughes stuff now, and look forward to your Enlightened Moparian Guidance.

Gerald
 

twostick

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65 MIGHT work but it's more valuable to convert a ball and trunnion pushbutton trans to slip yoke. On second thought, it probably won't work because the park cable mechanism is in there. I see no reason a 66 and newer won't work.

What's wrong with the one you have?

Kevin
 

Gerald Morris

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65 MIGHT work but it's more valuable to convert a ball and trunnion pushbutton trans to slip yoke. On second thought, it probably won't work because the park cable mechanism is in there. I see no reason a 66 and newer won't work.

What's wrong with the one you have?

Kevin

Nothing is WRONG with it, but I'm curious about whether certain small improvements made over the 11-12 yrs since it came off the line would make it preferable for use w the motor it came with.

FYI, despite having been made in late 1965, its assuredly a 1966 model transmission. These are somewhat unique.

My decision tree consists in part of considerations regarding the difference in engine balancing, and fitting things together. The 1966 has fewer splines (19? IDK 4 sure just now...) than the 1967 and later transmissions do for example. I KNOW I can get a B&M flex plate to accomodate things, if I want to go that route. The price is modest too.

All this data must be obtained, then tested against the reality of what I have. THEN I can make some good calls. Thus this thread for now.
 

twostick

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Nothing is WRONG with it, but I'm curious about whether certain small improvements made over the 11-12 yrs since it came off the line would make it preferable for use w the motor it came with.

FYI, despite having been made in late 1965, its assuredly a 1966 model transmission. These are somewhat unique.

My decision tree consists in part of considerations regarding the difference in engine balancing, and fitting things together. The 1966 has fewer splines (19? IDK 4 sure just now...) than the 1967 and later transmissions do for example. I KNOW I can get a B&M flex plate to accomodate things, if I want to go that route. The price is modest too.

All this data must be obtained, then tested against the reality of what I have. THEN I can make some good calls. Thus this thread for now.

They went to 24 spline input in 67. Easy upgrade there, just swap the pump and input shaft assembly. Lots more converter choices then. The other nice to have change is the part throttle kick down which I think can be retro fitted to the 66 valve body.

Engine balance is all in the converter and harmonic balancer. The B&M flexplate is the answer there.

Kevin
 

Gerald Morris

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They went to 24 spline input in 67. Easy upgrade there, just swap the pump and input shaft assembly. Lots more converter choices then. The other nice to have change is the part throttle kick down which I think can be retro fitted to the 66 valve body.

Engine balance is all in the converter and harmonic balancer. The B&M flexplate is the answer there.

Kevin

Food for thought! Actually, the old 66 tranny has ONE egregious wear issue, now that you mentioned the part, the pump body in that old aluminum is rather worn out. The shop I hired showed that to me. They did nicely w the rebuild, but I do remember being advised that there weren't too many more rebuilds left in that old housing.

SOME engine balance is in the forged crankshaft of the older engines, which was why there was relatively little need for big weights or dampers on the older setups. I'll explore the expense of using a forged crank in the 400, to be sure.

I really look forward to this project!
 

70bigblockdodge

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You can use a forged crank with no balance issues. Reason for the weights is because cast iron is not as dense as forged steel, and they could not make counter weights large enough to internal balance. The 400 & 440 both used same torque converter weights. If you have a good 383 crank I would drop it right in the 400. The tailshaft when slip joint first arrived they were greased and isolated from trans fluid. I have never actually seen this set up, but have heard of it. 19 spline inputs are a PITA, one because of no availability of cheap used converters, two the pump support is narrow up through 1970, not that the narrow support is bad in regular/stockish use, the combo of 19 spline and narrow support would be a deal breaker if I had all 1971 up stuff available. The later model stuff, not sure when, switch speedo drive gear/housing, that can be switched with older as long as gear matches housing. I believe 1966 and earlier valve body does not have the provision for part throttle kickdown. 1971/72 it became standard on big block trans, so again a plus for later model trans. I would not go chase a later valve body just to install part throttle kickdown, you can just move lever to 2nd at any time, if your in there and provision is there for it sure why not.
Another point is: I am using a B&M external balance flex plate on my 400 and neutral balance converter. It does seem to have a harmonic/vibration (slight) at a certain rpm that I don't remember when I welded the weight to my original 383 converter.
Hope this helps.
 
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65CopCar

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65 MIGHT work but it's more valuable to convert a ball and trunnion pushbutton trans to slip yoke.
FYI - 65 is not ball and trunion. First year for slip yoke. The manual trannies still had the ball and trunion in 65 but not the 727s. That is why the 65 727s are very attractive for previous years in order to get rid of the ball and trunnion but retain the cable shift.
 

Gerald Morris

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You can use a forged crank with no balance issues. Reason for the weights is ,,,,
Thanks. Yes, I'm well aware of the difference between nodular cast iron and forged steel shafts. I PROBABLY WILL harvest one of the 3 forged cranks I have for the 400, and have it cut .010" down for that Maltese Cross spec on the block, UNLESS the rotating assembly in that motor is in good enough shape as it stands to just clean up close and run. This is TBD.

You begin to see some of the issues facing me as I weigh the merits of using the 1966 trans or not. I reckon I can peel the 1968 tranny off the cracked '68 block, and count the splines, to be SURE of what I HAVE there. I might use that one, as the tailpiece is identical to the late 65 built, '66 model tranny I currently am using....
 

70bigblockdodge

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The '68 will have 24 spline. You can check with the PK number on driver's side pan rail
Screenshot_20220528-110205.png

Here is a screenshot of the column you should be in. Complete PDF is on my Mopar I believe. I keep it downloaded on my phone to id any trans I find for sale, might be a gem with good pieces.
 

twostick

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FYI - 65 is not ball and trunion. First year for slip yoke. The manual trannies still had the ball and trunion in 65 but not the 727s. That is why the 65 727s are very attractive for previous years in order to get rid of the ball and trunnion but retain the cable shift.
That's what I meant. Use a 65 tail housing on a 64 or earlier pushbutton to ditch the ball and trunnion.

Kevin
 

Gerald Morris

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The '68 will have 24 spline. You can check with the PK number on driver's side pan rail
Here is a screenshot of the column you should be in. Complete PDF is on my Mopar I believe. I keep it downloaded on my phone to id any trans I find for sale, might be a gem with good pieces.

Thanx big BIG for the ref. Heading to MyMopar for some more....
 
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