the trannys used in ranger/BII are different lengths. therefore driveshaft lengths will be different and since wheelbase of BII is short, ones from BII will not work for ranger. the front one might.
manuals are TK5, FM-145 and FM-156
i think it is the FM-145 that is same length as the A4ld auto.
your '84 ranger likely uses the TK5.
Wow. So much wrong with that information.
Lets start with the first paragraph. The transmissions from the Ranger and the Bronco II are the same assuming the model number is the same. And they use the same transmissions.
Manual transmissions are: TK-4, TK-5, FM-132, FM-145, FM-146 and M5OD. The TKs were the only ones used in 84.
The FM145 is 2 inches shorter than the A4LD. The 146 the M5OD are the same length as the A4LD.
The part about the rear shafts not swapping is correct. You will need to make sure that your new trans is the right length or you will need to find a drive shaft that is the right length.