back in the 70s and 80s I used a compression tester that a mechanic didn't have to thread into spark plug hole. It would just push in the spark plug threaded hole and when he cranked the starter it just swelled and locked onto the threads and gave a compression reading. had a push button to release pressure. Worked like a dream. I can't find one today. Anyone know where to get one?

 

Company called Mityvac still makes em. Several different styles.
Grumpaw

 

Had one years ago but preferred the threaded one I had, well still have, lol
It has longer flexible hose and as most know you don't have to have threads TIGHT just snug, hand tight, to get usable readings

Never about high number just about the average of all cylinders, so as long as all are tested the same way you get usable average

 

I went to mityvac web site and its not there. I'm not talking about the rubber cone end if you are about that.

 

The regular tester will not fit into spark plug area because it appears to be too long to reach. thank you. MY vehicle is 00 ford ranger 3.0L

 

I use one similar to this one:
Uses standard air hose fittings so can also be use for leak down tests, had it for 30+ years now

Never ran into an engine it wouldn't work on, even the Mustangs, lol, but you had to drill a hole in inner wheel well to get to back spark plugs