We have a '59 diesel and I'm about to pull the pump to see why ours isn't lifting. I believe the pump is a multiple piston type and it's located in the "belly" of the housing forward of the tranny. You should see a pan on the bottom. The AC manual and also the I & T manual have quite a bit of info on troubleshooting the pump and the system. I've never worked on ours, but as they say: "I fixin to learn"...In my case I have an 80 year-old mechanic thats going to look over my shoulder. If you don't have a manual, you need to get one. I might even have an extra one here, I'd have to check.