injector pump adjustment question

[Terry Donlin]

I'm swapping a '81 J engine into a '91 suburban that had a C engine and I need a little advice on the electrical connections on the injector pump. On the passenger side of both the old and the new pump is a black puck shaped object which is attached to the injector with two fasteners. The holes in the puck shaped object are slotted implying it can be adjusted. I'm thinking about transfering the '91 "puck" to the "81 engine because the '91 puck has an electrical connection to mate with the wiring harness that the '81 doesn't. What is the black puck? and how would you adjust it after swapping them?
Or should I swap them?
Thanks, Terry

[kojo]

I think it's somekind throttle position sensor or switch (in my 84 engine it's switch) electricity for torcue conventer clutch solenoid goes thru that, i don't have adjustment Guide, but i think switch should be open when engine idles