i never knew this engine existed,was it installed in any gm trucks or was it an over the counter replacement engine?

It's relatively new and available over the counter. I think was mentioned on a thread here in past month or so.

My understanding is that its an OTC deal. Mine is a 2015.

Looks like this company uses it

http://powertrainintegration.com/pi-thon-8-0l-v8-lpg/

what was the price tag on it,looks interesting.

$5977

Mine was kind of a long story... A builder owed a friend some money and gave him this motor for part of it. It was supposed to be a 540hp 502ci. I pulled the cam to put in one with a fuel pump lobe and discovered it was a truck cam. I pulled the head and it had small valves with Mk IV head gaskets. My buddy is going after the builder and charging him for my cam and heads. I paid $2,500 for it. He gave me a Lunati cam and lifter set along with the heads. The cam kit was $1,100 alone. I figured I still am doing well at $2,500 and some labor.

It interested me so I did some googling... seems to be built for cng/lpg and 4500 rpm max rpm (most likely because of cam im guessing) also from the piks of it online (the sale version not the op's) it looks like it has peanut port heads?? 19256827 though its hard to tell looking at a tiny screen

Though there might be a few different versions of the motor.

I really find it strange though as I thought gm had backed away from the bbc

I think there is a market, or demand, for alternative fuel engines. The bbc gas platform, works well on alternative fuels. Thats why valve seat materials have progressed alot as well.

The light truck market may have got away from the gas big blocks, but in the school busses, rvs, and things like that, it seems like they may be wanting to get away from diesel in some circumstances. The small LS engines they use in light duty pickups now, just wont make the low rpm power the big block engines can.

There are a few different versions. Mine had these heads. P/N: 19256821 2.06"/1.72" valves.




Here's the new heads: