gmc228,
On my GMC 228 the bottom oil filter line connects to the passenger side of the block. The top oil filter line is routed across the front of the block and connects to a fitting on the driver's side of the block.
Check out these
photos .
Edit: Here's a
link from oldgmctrucks.com that may help too.
Let me know if you have any other questions.
Good luck,
