I used my Harbor Freight tester just the other day on my 1981 diesel engine. It looks slightly different than the 93644 one. I bought it ~3 yrs ago. I don't know how it works on your engine, but if the injectors are the same, and you have a straight shot down to them (remove your intake?), it should fit. I don't know how "absolutely right" it measures, since the compressed volume in a diesel is very small, so any slight difference matters. I measured 400-410 psi in all 5 cylinders, but when I tried with an old heat shield installed, I measured less, (~375 psi). Seems like if the "injector simulator" seals on the tapered edge, having a heat shield in would decrease the volume and increase pressure. No instructions, so I figured w/o heat shield was the correct method. With the hollow ring on, the injector simulator looks identical in dimensions to a Bosch injector body. I did have trouble with the quick-connect popping off, so had to hold it down with my hand while my wife turned the key. That is an easy fitting to find, so could be changed. I never tried the glow plug adapter, since that would be harder to install, though might give more representative pressures.