I purchased a 1980 Toyota 4x4 a few weeks ago. It wasn't running too well as I mentioned in an earlier post. An area mechanic put new plug wires and plugs on and that helped a great deal. He also ordered a new rotor and rotor cap but it wouldn't fit so he figured they had sent him the wrong one. The parts store sent another. It was the one listed for the 1980 20R but it was too big. I took the existing rotor cap and rotor off today and carried it to a couple of parts places. They both pulled the one for the 1980 20R and it was too big. The 2nd one decided to try one for the 1979 20R and it was a match. He said that even thought the truck is a 1980 "model" it could have been manufactured in 1979 calendar year. I checked the ID plate on the driver door post but it says the following (as best I could read):
INC. VEH. MFD.: JUL/80
GVWR(LBS/KGS): 4550/2063
GAWR(LBS/KGS): FRT. 2630/1192 WITH H78-15 B__

TIRES,15X5 1/2-JJ RIMS, AT 32PSI 220KPA COLD.
RR. 3000/1360 WITH H78-15 8__

TIRES, 15X5 1/2-JJ RIMS, AT 32PSI____
VIN: RN37-039904

So, what do I have here?

BTW, when I put the new rotor and rotor cap on, the tachometer (which had previously been very intermittent) seemed to work fine. It cold idled at 3,000. I drove it around the block and the idle was at about 1,800. I will have to wait until next weekend to check it out further. The truck definitely seemed to run smoother but still had that hesitation or dead spot in the acceleration unless I had the rpms up around 3,000 when taking off from a stop or when shifting gears.

Is this normal or do I still need to keep looking? I'm considering checking all vacuum lines, wiring harnesses and such and maybe replacing them. This is a 1980 and hasn't had all that loving of care.