I think another reason why you dont see many big blocks on here is packaging. I have no first hand experience with it, but it doesn't seem like you would be able to swap out a 4.8l for a BB the same way you can swap out a 4.8l for a 408ci. For some of the guys, it only takes a day. Load up a new tune, and go have fun. You can get fairly large cubes in a small package.

 

Or, because you can put in a cam and a few bolt ons a go have fun.
My truck has a near stock idle and I get 17 mpg on my daily commute while I make ~ 515hp with minimal mods.

Someone with a stock short block 6.0 could do similar results as mine.

 

Good point on the packaging. And it seems a darn good return on investment-time/money.

Now here is question that I have not been able to get a good answer on. Remember I am a Jeep guy that uses his truck to tow and haul the family. So please excuse the ignorance on my part.

Some HD2500`s have 8.1`s in them with 4L80E`s.

My HD2500 came from the factory with the 6.0/4L80E.

If I wanted to swap a 7.4/454/Dart/old school BB would it bolt to the frame/trans ? Or are the frame mounts different for the LSx series blocks ?
Understand the engine mount that bolts to the engine itself would be different. But how about the frame side ?

How about the 8.1`s ? Same question.

So if it would bolt up. I could conceivably put a 581/628 Dart in my HD.

I ask in that if I found a 6.0 Suburban donor. Could it be converted to BB power ? Or even dropping the cubes into the HD.

Thanks !! You folks have been really helpful/knowledgeable.

 

I believe the 8.1s share the same mounting locations as the older BBCs, as well as the bolt holes for the bell housing. So I believe it would be doable.... But many (including myself) would beg to know why someone would want to take such a huge step backward in technology... Just for low end tq? Like everyone has said, there's better ways...