Mack MR688 Or Terrapro Cabover?

This may sound like a really dumb question but I would like to know if anyone has ever seen a mack big window turned semi. I run regional with a lot of city driving and it gets rough getting around some of these places in an on high truck. So my plan was to get a used Mack MR688 throw a 48" or so midroof on it and add a 5th wheel. I do also want it 6x6 for winter driving and for FEMA response jobs eventually Any thoughts on whether it's illegal or just not feasible?

Seen plenty of those (or similar models) as semi tractors, the Postal Service used them almost exclusively for years. However they are/were all day cabs. I’m no expert, but given that most of the engine and a good bit of the intake and exhaust hardware is behind the cab fitting a sleeper would be problematic at best, and a huge maintenance nightmare if you managed to get it mounted. I suspect the cab lacks the structure to support an add on sleeper box, so you would probably have to mount the sleeper separately, which leaves a seal type connection to the cab which are prone to leaks.

I’m sure it could be done, but in the long run would the trade-offs be worth the benefits?

Gregg

I have seen those as yard trucks, I was wondering about a sleeper version. I was thinking the same thing, had a few different ideas for seals or even hydraulic cab lifts with cut out panels in the floor for fluid checks. Moving the exhaust stack and heat insulating it against the cab, etc. My other option is the granite which I think I'm going to do because it's significantly less modification. I'll just make it old fashioned with a new grill like the old 1940's Macks, bubbling it out and rounding off the wheel areas, adjusting the lights to match the old style. It's going to be cheaper, they make them in 6x6, and I won't have to work about a major project just for a short wheel based truck with some added traction when needed.

I also had worked on doing a commercial class bus conversion to an RV and it was ridiculous. I wasn't sure if I would need an enhanced inspection or the requirements for dropping the garbage box, adding a 5th wheel and a sleeper. So it seems more trouble than it's worth at this point.