put the complete 350/700r4 combo on Craigslist 2 weeks ago. Got one call asking if it was 2 or 4 bolt main. I wasn't about to drop the pan, hell I'm practically giving it away at $1,000. It comes with powersteering/fuel/water pumps w/brackets, demon carb, 3 yr old dizzy from skip white, 2 good starters, alternator, and extra used plug wires n cap/rotor (and ran great when I pulled it, does leak oil on rear main seal).
Anyway, I purchased an Android snake camera and put it up through the oil plug in the pan to find out. Nice handy tool. Mine is wired, kinda wish I would have bought the wireless version for $20 bucks more. At 2 MP it's blurry at long distances, but anything close is fine.
Be nice to have when your out at the yards or where ever looking at LS 5.3's when you need to look at the pistons.
https://www.amazon.com/gp/product/B06WRNGYXY/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1