how do u tell the difference between a 42 re and a 46 re tranny????

 

Ram 1500:
If you have a V6 (3.9L) and your truck was built after 1995, you have a 42RE.
If you have a V8 (5.2L or 5.9L) and your truck was built after 1995, you have a 46RE.
If you have a V6 (3.9L) and your truck was built before 1996, you have a 42RH.
If you have a V8 (5.2L or 5.9L) and your truck was built before 1996, you have a 46RH.
Ram 2500/3500:
If you have a V8 (5.2L or 5.9L) and your truck was built after 1995, you have a 46RE.
If you have a V8 (5.2L or 5.9L) and your truck was built before 1996, you have a 46RH.
If you have a V10 or diesel and your truck was built after 1995, you have a 47RE.
If you have a V10 or diesel and your truck was built before 1996, you have a 47RH.

The E and H don't mean a whole lot. The overdrive is controlled completely by hydraulics on the RH, and partially by electronics (and the rest by hydraulics IIRC) on the RE.

This, of course, only applies to automatic transmissions and not manual (or "standard") transmissions

 

i'll ask two more questions.

suppose you're standing at a junk yard and you're looking at 2 transmissions side by side. one's a 42 and the other is a 46. how can you tell them apart ?

now suppose ones a 46rh and the other is a re. how can you tell them apart ? electrical connectors ?

 

I believe the electrical connectors changed every couple years, so not sure how you'd be able to tell from those unless you were familiar with all transmission related electrical connector changes from 1994-2001.

I believe the RHs are longer physically than the REs. Will do more research and see what I can turn up.