FORGET about the lockup converter! According to Chrysler, it's only worth about 3% gain in fuel economy. The other side of things is that the splines in the torque converter need to be correctly heat treated or they'll fail! Takes a different front pump, too.
Chrysler did their research on lockup converters on drag race cars, from what I've read, but they never put it in an HD application, even real police or trailer tow package cars. PURELY a fuel economy EPA mpg thing.
When the splines suddenly fail, you coast to the side of the road and call somebody. That's happened to me TWICE on my '80 Newport. The first time, I was close enough to the house that I coasted to the curb, parked it, and got another one of my cars to drive back to work.
The second time, I was three blocks from the house, so I walked home, called the local trans shop, called a wrecker, got another car and went back to work. Best just to NOT get that done as the added gain in fuel economy is not worth being stranded.
Part throttle, that happened in '71 and is a valve body issue. Easy to add.
Rebuild what you have. According to a friend who was well-versed in '65 TorqueFlites, one of the things they did in '66 was to use wavy steel plates in the clutch packs. This softened the shift a little, to be more "GM-like" as they also softened the spring rates slightly for the same reason. IF yo9u know how yours now shifts, you'll notice the slight softness or "less crisp" shirts. Using gthe '66 and later TFs as a reference point, it feels like a more positive shift, although most TFs have positive shifts already. '65s, just a hair moreso.
As for the OD automatic, unless you have a 3.73 rear axle ratio, the OD won't have enough road speed to engage and not lug the motor, Now, if you put fuel injection on it, then you're not relying upon air flow through the carb to meter fuel.
It might seen better to do the OD or lockup converter, but I feel you'd be better off just doing a quality rebuild on what you have, your '65 TF, maybe some better frictions and a better-quality band, but not much else away from factory specs. EVERY trans builder seems to have their own "tricks of the trade" that "make things better". Some work, some don't, so the best thing is a quality OEM rebuild, maybe using a B&M "master" shift kit kit as a possible upgrade. There ARE less expensive kits, but after a friend used one on his '79 Corvette, it acted just like a more HD factory trans with more positive shifts. Kind of like a good TF might have, but this was a TMM350. The added money was worth it, compared to the $10.00 shift kits back then.
CBODY67
