Yeah, it'll be slower than a sd. I had several with this combo. All were 3/4 ton with the turbo 400. They tended to crack the main webs if running the 410 rear. the 373 is what you want if you intend to tow. I towed my 24' wilderness tt many miles with mine. It would run about 65 floored but would do it all day.

20 is possible with the od tranny prolly.

342 diff would be too tall if you wish to tow a tt with it but for just driving around it would be fine I suppose.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.