80's A998/A999 into Early A

fishy68 said
all 904 transmissions have the same 1 to 1 high gear ratio so the 80's tranny isn't going to affect hwy cruise rpms or fuel mileage. But it may have the low 1st gear set so it could help take off. In the 80's Mopar used some really tall gear ratios in the rearend. That's why it cruised at such a low rpm compared to your Dart

BTW: the leak your describing is called a static leak. Two of the most common problem areas that cause a static leak is the o-ring seal on the dipstick tube and the shift shaft seal.

No no, sorry, should have clarified. I pulled the 318/904 combo from the 85 Chrysler, and dropped it in the Dart. Have an 8 3/4 with 3.23's in it. When driving, I remember 3rd gear would start to rev higher, then kick down a little making the RPM's a little lower.

The Valiant has a 7 1/4 with somewhere around a 2.90 gear.

I'll check both those areas on the transmission though.