I am sure this will make me sound stupid but oh well, the gearheads I know cant answer or they never cared about this, but what is the lT1 or lS1 or any of the others mean, as far as my old man ever said was for the most part was that a 350 was a 350 was a 350. and so on until they started throwing computers at everything. I realize they changed block designs but a 350 was the same for a very long time.
thanks Brian  

It's just an identification code. GM has used them for years. There's the Z11, ZL1, L96, L88, LS6 just to name a few.

GM has brought back some of these codes that were used for muscle cars in the past. There has been two LT1's. The early LT1 was a high-performance 350 used in '70-'72. The later LT1 was a Generation II engine that had some slight design changes from a Gen I 350. Such as new aluminum heads with a reverse-flow cooling system and they moved the distributor to the front of the engine.

The LS1 is a Generation III engine has next to nothing in common with the Gen I or Gen II engines. The bore centers are the same, but I think that's all. The LS1 uses an aluminum block, 15° heads with a completely different port and chamber shape, it's a Y-block design with a front-mounted gerotor oil pump and completely different crankcase and oil pan, etcetera.  

thanks, it just seems anymore that is all you here, and I wondered why, its bad enough that they dont even use cubc inches anymore,  

another throwback to the golden years of horsepower is either the gen 3 ls6 or ls7. originally it was the hi-po version of the 454 ran in early 70's chevelles