Ok. For reference, the Tahoe was only available with 3 engines. If you know the VIN of the vehicle you pulled it out of, you can look it up.
The 8th digit of the vin would be:
V: LR4: 4.8L
T: LM7: 5.3L (non-flex)
Z: L59: 5.3L (flex fuel)
The LS1 accessories will mount to any of them and *most* other parts will match. The exhaust manifolds and fuel injectors are the biggest things that can give you issues if you buy LS1 parts for those engines.
Unfortunately, the only way to tell the 4.8L apart from the others is to pull the heads. The Flex vs Non-Flex have different injectors, but are otherwise the same.
