I swapped a 6.0 and 4L80e from a 2006 Silverado into my 79 Silverado. easy swap. Exhaust manifolds worked with just a little notch on the frame on passenger side. Most of my time was used finding small items and fittings for trans cooling lines, power steering fittings, and such. Not difficult, just time consuming. Plan well and read all the post. Good luck. It is worth the effort.