You are correct, the LB7 which is what I had, were a head ache. I had constant problem of leaking injectors which lead to diluted oil among other issues. I had mine in the shop 3 times for this problem. They assured me it was no big deal but I always wondered what damage was done to internal bearings running in diluted oil?
The LLY has not had the best reputation either. It has had head gasket problems, and over heating problems which GM now owns up to and covers under warranty. There were also glow plug issues that seemed to be cured once replace. The late LLY which only ran for about a year fixed most of these problems and carried over to the best Dmax out there, the LBZ.
Chris