Conversion of 6.2L CUCV to HMMWV and upgrading from 3L80 to 4L80E transmission

[Majorrdad]

Recently purchased a 1987 two man M998. Found a yellow tag 6.2L CUCV engine and a 4L80E transmission. It is my understanding, the CUCV 6.2L can be converted to fit the HMMWV by changing the exhaust manifold, 24V injector Shutoff and tach drive. If there is any additional items I need for the engine conversion please let me know. The current transmission I have is the 3L80. Want to upgrade to the four speed 4L80E, could someone let me know what issues will need to be addressed to make the transmission conversion.

Thanks,

Julian King

 

[NDT]

The pulleys are different between the two engines as well. The 4L80E is a very involved swap. It is longer, so driveshafts have to change. The controller and harness are the big ticket HMMWV-only items. And you need a dual voltage alternator to power it. Hopefully someone who has actually done this will chime in.

 

[Majorrdad]

Thanks for the info, do you know if the transmissions have the same transfer cases?