I bought a new L98 shortblock and am not sure which oil pressure sending unit I Should use. First I got the one for an 89, the year Camaro I have, but it didn't thread into the correct hole, it was too big. So I brought that back and got the sending unit for an 88, but I got the one that goes on the block right behind the manifold. There was a hole right next to the filter but it was plugged. The 89 Sender fit in there. Is where #21 is in, where the 88 and lower sender goes and where the orange arrow, where the 89+ sender goes?

I can just use the pre 89 one i guess, it's only $9 from gmpartsdirect, but they want $6 for one of the fittings(#13) to attach the guage sender(#11) to the block. Plus I'll need #12 also but there is no part number listed in the parts and illustration manual. Would I be able to get those fittings at a car parts store?

both holes should be 1/8"NPT

The hole that #21 goes into is smaller than the hole that the orange arrow is pointed to. Would it be ok to put the sender where the arrow is? Where #21 goes into you can see through it, it goes into the back of the engine. Like were the flexplate would be. I don't see how oil would even get to there.

i suppose you could try putting it there. I donno if it goes all the way through, though. Put a plug in place of the hole intended for the sender so oil doesnt gush out. Hell, for that matter, you dont even need a sender. i think all the newer thirdgens just use that sender as a backup for the fule pump turn on in case the computer stops sending a signal to the fp relay. I just blocked the hole off with a screw and some thead sealent because i didnt feel like getting a new sender. Runs fine without it.

Oh, as for that #21 hole, it should come right off the passage to the oil pump.

Well with the 89+ engines the sender serves as the sender for the guage also, not just the fuel pump backup.

If i use the 87 - 88 setup and I don't use a sender I would still need the fittings so that I can connect the sender for the guage that is up near the intake. Does anyone know where I could get them from, besides GM?

huh.... didnt know that about the newer setups. Yeah... if you use the sender up by the intake, you will need one of the elbow fittings for the sender. Try parts stores around your area. I found that the mr. auto near me has lots of obscure parts in their reagonal warehouse.