What is required to put a 74 Duster 4 speed in a 71 Duster 4 speed car?

I am wondering if there is a difference in bell housings, pedals, clutch.

Is the transmission identical?

If its a 4 speed to 4 speed its a direct bolt in...
Make sure its a 4 speed and not a 3 speed OD. That will require a bell housing change.
I'm sure some know it all will reply to tell us it won't fit...

Thanks. I don't know if the 74 is a 3 speed overdrive.

I do know that both fender tags say D21.

Get the trans and bellhousing from the 74 if available. Should solve the retainer bearing size issue.

Brewers shows the pedal assemblies as different, dunno what is different or if they are swappable as an assembly. Might want to talk to them and see if they can help.

http://www.brewersperformance.com/contact.htm

Mopar change the gear ratios in the B and E bodys in 1971 to match the AAR Cuda and T/A Challenger ratios, not sure about the A bodies though They also changed the synrcho assemblies in either 1969, 1970 or 1971 as well as the side covers in 1971 to the GM style . I would pull both side covers and take a good hard look at all the gears in both boxes and go from thier Take the better box

AS far as I know the OD came out in 1975, so a true 1974 4 speed should be a normal 1:1 box.

There were some 75 1:1 3.09 low gear trans put in cars, several I have had used the 5.125" retainer also, fwiw.

I went thru a 73 A-body 4 speed back in 2010. It was a "close-ratio" gearset. IIRC, that started in 73. Gears were hard to find. Repro gears are available for the 71 trans you have access to. It's cheaper to rebuild than a later trans.

Personally, I'd get both and use the best from each. The sidecover/levers may be better from the newer one.