Hello i have a 3.9L dakota and the **** 42RE transmission. my tranny is on it's way out and i'm going to buy a new one, but i'm also changing the engine in a few months time. now what i want to know is the transmission interchangeable from engine to engine, the engine i'm going to is a 5.2L. I've seen allot of posts about the 45RFE/ 545RFE and was thinking if i could get away with it i would put the better tranny in as opposed to just doing the 42RE again and just having to fix it again in a year or 2.

Well thanks for any info you can provide.

 

42RE/44RE are the same, a 46RE may work, but may need to replace the drive shaft and flex plate. A 45RFE/ 545RFE will not work. if you end up putting a 46RE trans in the truck, your 3.9L motor may not have the horsepower for the 46RE trans.

 

the 45rfe is for the 4.7 and 5.7L If you plan on doing a better swap like a hemi do it all at once... A 46re is what they use on the fullsize trucks. So it might be a bit heavy but Im sure the 3.9 will drive but it will be even more sluggish than it is. and I must say the 42re is junk so even if you put that in i would recommend against it...

 

Nah man i hear that i don't want it i was just wondering if they were interchangeable, but you guys told me what is and isn't so i know what not to do thanks and no it wont go back in there.