Why diesel? If you have a 318 powered truck its atleast 14 years old trucks have come a long way in the last decade, just the next body style dodge is way more capable.
A 3/4 ton HEMI or 6.0 GM truck will be way more capable than what you have, cheaper to buy and probably maintain.
The 545rfe or whatever it is, is pretty robust behind a gasser in the dodge, mine has 300K and has been used to tow a lot, its pulled the old Z28, my old 69 firebird and even my dads old suburban on a flatbed, and its only a 4.7 its pretty slow. And a Hemi tows WAY better, and a 3/4 ton chassis would be even better than my 1500.
