I have an M35A2 and suggest ditching the diesel engine (135 hp) as it has a narrow power band that is in the 1800-2300 rpm without the gearing needed for slow going anyway. I installed a 496 Vortec engine (same MPG, quieter, way more flexible) with a 6 speed ZF trans and that alone brought the...
All it takes is imagination, a bit of money and lots of 'fun' work. I did it and, although I doubt the project will ever end, in the mean time it is a hoot!
Sitting on my butt trying to recover from laryngeal cancer surgery (no more vocal cords, total rebuild) ~ time heals everything although not always the way we would wish. But as Mom used to say "if wishes were horses, beggars would ride."