Allow me to rephrase.... What does D99 represent? I don't recall EVER seeing that code
My first guess would be special order transmission.
dunno if this helps...the D99 thing also caught my attention. 30 minutes of google searching yielded nothing definitive other than the "usual (and useful) suspects " on fender tag decoding.
"D99 - Special Order Transmission" helps but still doesnt say what it is. I did notice that "D99" and "Road Runner" also came up together several times in different enthusiasts threads.
Recall also the thread discussion on FCBO recently where the existence of a "R/B 904" was swatted around..a member posted very useful technical information on the various differences between the "regular" and "HD" 727's. I hope he sees (or someone else who really knows) this and weighs in.
While it may help or be of no consequence other than to muddy the issue, I found this thing from 1970 (hard to read without magnification but has some neat data) that shows a "high-upshift TorqueFlite" standard on Sport Fury GT and optional on Road Runner.
I know..."High upshift" does not equal "D99" and i will freely admit I am out of my depth, so please "curb your enthusiasm" to slap me around in this thread.
But we all can reasonably infer it likely was "heavy duty" with respect to its innards yes?
So maybe this "D99" 727 had a "high-upshift" feature (given the powertrain was hauling around 5500 lbs of car and 2500 lbs of people and luggage, etc), plus 4-pinion planetaries (and other features - HD discs/plates/bands - like the HD/Police D32/D36 trannies had), and other/different springs to soften the otherwise sharp shift points (it is a limo after all so you cant snap necks shifting) given the engine and rear-end specs the vehicle had?
Wonder what 727 tranny flavor went in truck/vans/motorhome chassis in this era - clue there to this one?