3/4 ton

Discussion in 'Trucks and Trailers' started by mycave, Mar 16, 2000.

  1. mycave

    mycave LawnSite Member
    Messages: 34

    Can any one tell me if there is a way to tell if I have a heavy duty or a light duty truck? The truck is a 1986 3/4 ton 4x4, dana 44 up front and 14" GM rear. It also has 8 lug 16.5" rims. Im not sure but I have heard there is light and heavy duty trucks in 1986 Dont know if source is dependable. Thanks for the help!
  2. John DiMartino

    John DiMartino LawnSite Silver Member
    Messages: 2,555

    What is GVWR? HD's are at 8600 in 3/4 ton GM.LD 's are at 8500 or less.The tag is on the door,or the option sheet on the inside of the glovebox door.It sounds like you have the HD.I think all LD pickups made by GM were 6 lug,im not positive though for 1987 and older.<p>----------<br>John D<br>
  3. plowking35

    plowking35 LawnSite Bronze Member
    from S.E. CT
    Messages: 1,687

    What tranny do you have? the HD came with a 400 3 sp auto and the LD came with the 700r4.<br>Sounds like someone changed rims on you the rims should be 16 not 16.5.<br>I have a 86 k-20 with the turbo 400 and its a 8600 gvw.<br>I also have a 84 k-20 and it has 8 lug rims but only the 7800 gvw.<br>The vin# also should have the gvw option code<br>Dino<br>Dino
  4. yortengel

    yortengel LawnSite Member
    Messages: 216

    The HD Truck has a different rear axle than the LD. The LD has rear brake drums that just slide off (after loosened with large hammer) The HD has a full floating rear axle. which means there are two bearing in each axle hub. both have 8 lugs, and both came with 16in rims. Also PlowKing is right, the HD should have a THM400 Transmission. But there may have been a few that were made different. <br>Troy
  5. mycave

    mycave LawnSite Member
    Messages: 34

    Thanks for the info I made a mistake I have 8 lug 16&quot; rims and a 700r4 I couldnt make out tags on the door or the glovebox what on the vin# code would help? Is it possible to order the heavy duty with the 700r4? The motor is the 5.7 LS9 if this helps
  6. EDL

    EDL LawnSite Member
    from MA
    Messages: 110

    I beleive also the HD would have one or two more leaf springs in the rear, but i do not remember the count on them
  7. John DiMartino

    John DiMartino LawnSite Silver Member
    Messages: 2,555

    If you have the 700r4,you probably have the LD,does it have a full floating rear?My friend has an 81 HD with a TH350 and NP203,he eats TH350 's because his GCWR is 30,000+ sometimes.He is finally getting smarter and stops at about 20000.He pulls this with a 350/4BBl,very slowly and squirmy on the road too.<p>----------<br>John D<br>
  8. Doug406

    Doug406 LawnSite Member
    Messages: 134

    All things being equal, what does it matter what the classification is, LD or HD? The truth is a 14 bolt full floater(triangle shaped rear cover) and the 400 turbo(Texas shaped pan) are the heavy duty parts.
  9. MTCK

    MTCK LawnSite Senior Member
    from Idaho
    Messages: 254

    Well, if you have the 700R4, I'd say it's a light duty. Also, even if it was a heavy duty, you wouldn't get the full floating 14 bolt, cuz chevy started only putting them in the one tons around 81 I believe. So you have a 9.5&quot; ring gear semi floating 14 bolt rear end, a NP 208 aluminum chain drive t-case, 700R4 tranny, and it should be a 10 bolt front end (not a dana 44) with two little taps on the bottom corners of the diff. All in all, not a bulletproof setup, but take care of it, and you can haul pleanty of stuff.
  10. Chuck Smith

    Chuck Smith LawnSite Senior Member
    Messages: 849

    Well, my favorite subject, heavy duty! Hmmm, where to start...<br>Well, first of all, the 14 bolt has been around a long time. The FULL FLOATER. My 77 Chevy came with one from the factory, as did my 80 GMC. There are two different size brake shoes used on the full floater. One is i believe 11.something inches long, and the other is 13&quot; long. My 77 has the HUGE 13&quot; shoes, and my 80 has the smaller 11&quot; shoes. My 77 has a GVWR of 8,400, and my 80 has a GVWR of 6,800. Big difference, yet both are 3/4 ton trucks, with 16.5&quot; wheels. I don't think GM used the 16&quot; on pick ups until 88. Back then I was a tire monkey at a local shop or two, and never mounted a 16&quot; tire.<br>To answer mycave's other question, there is a way to tell from the VIN #. One of the numbers represents the vehicles brake system capacity. <br>I have pictures of the Dana 44, the GM 10 bolt front, and the GM 14 bolt FULL FLOATER rear on my pages under Parts I.D.<br>Also, trans pans shape diagrams.<br>Oh, and you can decipher your own VIN# on my pages too.<p>~Chuck<p>----------<br>Chuck's Chevy Truck Pages - Snowplowing Central<br>http://www.chuckschevytruckpages.com/snowplowingcentral.html

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