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Recent content by nerfherder78

  1. nerfherder78

    custom/aftermarket door mirrors

    My brother had those on his old truck (picture below). Just did a quick search for '2 point mount mirrors' and found some "universal" ones on ebay and a few other online stores that are close, but clearly not the same. I don't know how well they would line up and bolt to the stock mounts, but...
  2. nerfherder78

    Diagram NOT the schematics please.

    I don't have any wiring diagrams, but I do have a spare harness for a '98 diesel that I'm looking to integrate into my '85 (haven't found any aftermarket fuse/relay centers that I like). It will be somewhat different from yours, but I have taken the back off the fuse center to trace some wires...
  3. nerfherder78

    1985 k20 needs new frame

    Any 1973 - 1987 long bed Chevy/GMC frame will work. '73 to '80 will need the front ends cut to fit the newer bumper. K10s may have slightly thinner metal than a K20 and aren't quite as strong, but everything will bolt up. The rear springs will also be shorter (52" vs 56" length) , but the...
  4. nerfherder78

    1987 duel fuel tanks electric issues

    An '87 should have in tank fuel pumps rather than an engine mounted one. It could be that the left pump is going bad, and the few minutes its running good is whats in the line from the right tank. To test the pump, switch to the left tank. Locate the switcher valve on the right side frame...
  5. nerfherder78

    1987 duel fuel tanks electric issues

    Sounds like the left tank isn't venting properly. When it does it try pulling the gas cap off and see if it releases any pressure. The tanks should vent through the charcoal canister, the lines run across the cab to the passanger side frame rail and T in with the right side lines before...
  6. nerfherder78

    TH350 No Engine Braking

    Looks like it may have to do with the valvebody and how it was rebuilt: Do TH350/400's have engine braking? Sounds like you'd need to talk to whoever rebuilt the trans.
  7. nerfherder78

    '86 duel tank GMC Gas Gauge issue

    Most likely the resistor on the back of the gauge: The GM Fuel Gauge Mystery 1965 & Newer | Pull it off and see if the gauge moves. There are 5 different color resistors, you'll want to replace it with the same color: Lt blue-123 ohms green -89 yellow-88 orange-86 blue black-81 I had one fail...
  8. nerfherder78

    1983 modifications

    You can put a '73-'80 front end on a '81+ truck, and vice versa, you just need the fenders, hood,radiator support, wiper arms and linkages, battery tray, etc. I don't remember all the differences; but I know 80's trucks have cutouts in the cab for the rear hood hinges, the frame rails on the...
  9. nerfherder78

    Diagnose rough running chevy R10

    You can replace the fuel filter without disabling the fuel pump, most often you just remove the gas cap to relieve any pressure in the tank. Typically you disable the pump then run the engine till it stalls to bleed off most of the fuel in the lines so you get less of a mess when undoing the...
  10. nerfherder78

    Bulb replacement in heater control

    There is one 168/194 style lamp on the back of the passenger side. The socket should twist out like the park lights on the fender. If you're agile enough, I don't think you even need to take the dash apart, just reach up from behind (I was able to do this with some of my dash lights back when...
  11. nerfherder78

    K10-K20 frame

    Went looking through my owner's manual, glove box and door tags on my '85 and didn't find anything on towing capacity, just a small section in the manual that said "ask your dealer for towing brochure.":rolleyes: I did find this looking online, supposedly from a 1978 owner's manual...
  12. nerfherder78

    K10-K20 frame

    I think I remember seeing a spec sheet that showed that the K20 frames were made from slightly thicker metal, but otherwise the dimensions are the same and they are interchangeable. Some K20s have rear springs that are 52" long like K10s, while most will have 56" springs. The axles are...
  13. nerfherder78

    '73 C10 auto to manual trans swap?

    The two most common manual trans you will find in these trucks are the SM465 and SM420. Both are 4 speed with a granny low gear (G-1-2-3). If you want overdrive, you can also get an NV3500 or NV4500 5 speed from a '90s truck. From what little I've read, the NV3500 will bolt in place of a...
  14. nerfherder78

    1974 GMC C20 lowering

    Control Arms: I converted my C10 to a C20 suspension a few years back. The lower A-arms are a direct swap (2 u-bolts to the cross member each), but the 3/4 ton upper arms have larger diameter mounting studs than the 1/2 ton. Front Springs: There were only 2 different coil springs used in...
  15. nerfherder78

    No Heat/No Dash Lights

    I looked through my wiring diagram and found a brown wire that runs from the fuse box splits and runs to the gauge cluster and the heater. If you have power at the heater and dash light fuses, this wire might be the issue.
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