Stop in for a cup of coffee
I was under the impression a 904 is same length as a 3 speed
Seems to be correct
3 speed which is also the same as a 4 speed.
Same FSM shows the driveshaft with the 4 speed shorter - but it also was only used with the 8 3/4 axle.
Probably need to look through the D.C. Bulltins for transmission lengths. Maybe in the one on engine swaps.
I guess the goof up here is that I have an 8.25 rear.
Probably have to look in a '73 up FSM.
727 is definately longer than 904.
273, 318 C.I. Engine 8 3/4" Axle
49.27"
340, 383 C.I. Engines 8 3/4" Axle
44.88"
The last driveshaft I bought I did like you - measured on the car. I bought from Denny's so probably just used the diagram on their website.
I also had the driveshaft I had been using so that and the books served as double and triple check.