Frame rails

[Kellerfarm2]

Ok I found a Mack superliner that my sold to wrecking yard a few years ago.. it all there but the transmission,  but has been chopped into pieces.. I found a 1996 Rd688 frame complete with 290 wheel base. Can I drop this Mack v8 400hp motor in or to narrow...

[AZB755V8]

Don't know about an RD frame. The RW and MH and CL frames are wider at the front to fit the E9 engine. There were some DM's with E9's as well. A strait frame may not work as is but anything is possible. Even the aluminum frame waistcoats E9 trucks had the front part of the frame wider. 

[JoeH]

All R and RD frames I've ever seen splay out wider around the engine and transmission. A good double frame RD should probably take a V8 just fine, but I don't know how much fabricating you'll have to do for engine mounts.

The v8 also makes a lot of heat, i don't think the R model radiator surface area is big enough to keep it cool if you're gonna work it hard. Superliners have that big square hood to hold a big square radiator. Not sure if a superliners cab and hood will bolt right to a Rd frame.  Might have to make some parts.

[Lmackattack]

Early R models had the 865/866 v8 as well as detroit V8 as a option. It will fit in the frame. the issue might be the hood is to short.