I'm in Sacramento and just used Diamond Diesel.
They pop test for free. They have a shop in Oakland, too.
2550 East 12th St. 510 532 8500
I was happy with their service. I took them a dozen from PNP to test.
Six were good. I threw the guy 20.00 for his time since they didn't charge me
and I wasn't going to have them rebuild the bad ones.

Jeff

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1984 300SD 300,000 miles--two tank WVO setup
2.88 diff & 500SEL anti-squat rear end