I have one in my 63 C20 behind a 292. I haven't put that many miles on it, but like it. My mpg went from 12 to 16 on the highway.

The transmission was used by GM from 82-86 as RPO MY6. There were several versions of it. The early(?) version used a bellhousing with both the GM and Mopar bolt pattern, rare, hard to find. The later trans used the std bellhousing. They come in either a aluminum or cast case. I replaced an SM420 and it required the drive shaft to be shortened about 9 inches. The shifter comes up on the left side of the tunnel just in front of the seat. Fourth (OD) is just off the seat. When New Process added the OD to the trans they used 3rd gear. To make it look like fourth they flipped the shift lever on the fork up. Reverse is also different, left and up.

I would suggest that when you get one to get the shifter with it. In particular you want the MY6 shifter or one from a Dodge van. These shifters mount close to trans case on the tail shaft, and higher up.

Larry

I don't own a vehicle that isn't old enough to drink.