Educate me on HMMWV 6.5L GEP conversion?

I have a 6.5 NA in my HMMWV and been seeing a lot about the 6.5L GEPs...

What is involved in the conversion?

What would I need?

Searched YouTube and forums, lots of info post conversion... couldn't find anything about one...

Your question is not clear. The only difference between a GM 6.5 and a GEP 6.5 are internal casting changes to prevent cracks. Possibly you mean 6.5 NA to 6.5 turbocharged?

You may already have a 6.5 GEP motor in your truck as it sits right now.
https://www.steelsoldiers.com/showt...5/page2&highlight=GEP+block+identifying+marks
Post 12 might be informative to you Dave.

As I stated, we have one HMMWV and we know very little about it...

I've read that the conversion to provide a true Park, and more speeds requires a new transmission, and engine and harness...

Oh, your question is "how to I convert my Turbohydramatic 400 transmission to a 4L80E Turbohydramatic transmission. Search 4L80E in the HMMWV forum, subject has been covered over and over.

There are 4 or 5 different engines and 2 or 3 different transmissions used as "stock" on the HMMWV's depending on year and if you count the Duramax (we won't). The engine is going to have little to do with your top speed. They all turn the same RPM, some just get to that RPM faster than others. The transmission and differentials will effect top speed more than the engine.

Engines
GM 6.2
GM 6.5
GEP 6.5
GEP 6.5 Turbo

Transmissions
GM TH400 3sp
GM 4L80E 4sp

Alternate Transmission conversion
700R4 4sp (no electronic controller needed)