81 2.0 swap to 87 2.6 possible?

Hello everyone. I have an 81 D50 that has the 2.0 in it with an auto tranny. I also got an 87 with the 2.6 and a standard tranny. I am wondering if I can take the 2.6 and put it in the 81 without too many modifications? Will the auto tranny from the 81 work with the 2.6....bolt up and such? I'd like to keep the auto tranny but can swap them over as well if needed. Any other modifications that need to be made other than a few wiring modifications that I can already see? Motor mounts and all that?
Please help as I'm new to these trucks and engines but am a very good mechanic and fabricator. Thanks in advance!!:)

Hi Firekatt, welcome to mightyram. Pulling the whole drivetrain and swapping it will be a no brainer. I think the only thing you'll need to work on will be a clutch pedal assembly and ensuring the tailshaft yoke matches the manual gearbox. There might be a difference in the gearbox mount but you have the '87 to pilfer parts from. These trucks are forgiving to work on and there are almost unlimited combinations of mods and swaps that can be done to them. I'm not 100% sure of what you'll need to do to mate the 2.6 to the D-50's auto trans but if the rear mounting bolt patterns match it should be simple.

Hi and thanks for the reply. I started stripping down the 81's 2.0 and from just looking so far, it looks as if the bell housing bolt patterns are the same between the 2.0 and the 87's 2.6. That should mean just changing out the flywheel and mating the 2.6 to the auto tranny in the 81. The only other thing I can see right off hand is needing to re-route some vacuum lines and wiring, mainly wiring for the alternator as it's on opposite sides of the motor. I'll keep this thread updated as I work on it and welcome any other input out there!!

the 81 2.0 should be a narrow block tranny (12.5" measurement on lower bolt holes) the 87 2.6 is a wide block (13.25" on lower bolt holes - both measurements are center to center). Welcome to the forum and the wonderful world of interchanging parts.

Sorry for such a late update, winter and snow prevented me from doing anything until now. Pennyman1, you are correct, there is a 3/4" difference in the bolt hole spacing between the 2 blocks. However, I may have come up with a solution...

Between the 2 blocks and transmissions, there is a plate that has the bolt hole spacing and pattern. Using this as a template, I plan on drilling new holes into the 2.6 block and tapping the upper holes. The lower holes will be drilled through, since there's enough flange to do so. As long as I'm very careful to not go through into any oil or water passages, this should allow me to bolt the 2.6 to the transmission the 2.0 was bolted to. I looked at the possibility of just swapping the whole drivtrain over, but to turn the 81 automatic into a standard requires a lot more fabrication for the clutch cable routing than just drilling and tapping a few holes. If anyone has done this kind of thing, please let me know how it worked as well as any opinions on my plans. Thanks :)

I changed the cab on Geronimo from a manual to a automatic cab, but he is a 5 spd. You will need the part of the firewall that the cable comes through to place it on the 81 firewall. the pedal assemblies will need to be swapped, and the transmission tunnel needs to be modified to allow the gas pedal to clear the side of the tunnel - the auto tunnel is wider that the manual tunnel. If you don't make the mod, the auto gas pedal ends up behind the brake pedal. you may also need to adjust the front driveshaft length to match the length of the tranny - if the 87 has a 2 piece shaft, just use it with the yoke.

Hi guys was jw about some of this myself. After searching for two weeks or so this thread has been probably the most useful thing I've found lol. I have an 81 ram 50 with the 2.0 and a four spd manual. I'm wondering what motors would bolt right up. 4g63 maybe? Also I want to change from a 4 to a 5spd. Just looking for the best route for a swap with direct fits

4G63, g63b, and 4g64 all will work with the 4 spd you have, as it is a narrow block tranny. There was a narrow block 5spd tranny on ebay - I can't find it right now though.

Pennyman1 you are a true hero. I have plans currently to purchase a remanned 4g63 and as for the 5spd I will pretend it's my daughter and go Liam Neeson until I find her haha. I'm a little new to forums like this but I plan to keep updates on the build as it comes along. Once again thank you very much for your time