So my '04 L67 in my '03 SS appears to have thrown a rod through the block for some reason, with only 72K miles on it. The car itself has 221K on the odo. I'm considering my options since the car is in really good shape otherwise and I've already done a lot of what needed repairing/replacing on it due to wear. I'm not sure if I'd sell it or keep it, but since I just bought an '09 LaCrosse I'll probably end up garaging it or selling it.

Should I drop in another entire used motor, go with a Jasper rebuild, find just the short block and use my existing heads? I'm concerned with the trans too - since there was no abrupt stop, blowing up, smoke, or other excitement involved I'm wondering if it may fine or if there is something I'm not considering in the trans that may need looking at. Also, if I find an L36 instead of an L67, will that bolt up to the HD trans?

Basically if anyone has been through this before, I'd like to hear some opinions on my various options.