The 4BT and the Turbo 400 sound like a good combo this would be much like the Chevy and Isuzu W4s that are very commonly used for light duty wreckers. I am sure that the Cummins 4-BT has all the power and maybe more than that little Isuzu and as for the Turbo 400 the only problem I see there is the lack of a PTO port. I work on M1051 fully up armored HMMWVs for the Army and these have the old style 6.5 turbo and a 4L80E transmission in them. The 4L80E is pretty much a new 4 speed turbo 400 and these M1051s have a dry weight of 12,000 lbs. so the turbo 400 should be fine as long as you can find your hydraulic power elsewhere.
