1983 k20 vin but is dually from factory don't know what parts to buy

[Artezio]

So I have a 1983 k20 which is supposed to be 3/4 ton but it's a dually from the factory I bought it from the original owner, so my question is how can it be a dually and only be a 3/4 ton it rides like a 1 ton and the vin decides to a 8001-9000 gvw, I need a new master cylinder and hydro boost but don't know what to buy, the service parts sticker is nowhere to be found so I only have this information to go off of, thanks in advance.

[big_al273]

something isn't original, factory duallys are all C/K or R/V 30s. Either the axles/suspension got switched or the cab or maybe just the Vin/ownership but something currently on the truck didn't come on that truck from the factory in 1983. I don't remember the dimensions off the top of my head but 1 ton frames are thicker material than 3/4 ton and have a taller frame rail under the cab whereas a 3/4 will have thicker frame rails than a 1/2 ton but the outer dimensions of 1/2 vs 3/4 ton frames are otherwise identical.

[hwh]

A 1 ton frame is 6 inches tall. And 3/4 ton frame is 4 inches tall be easy way to tell. But far as I know all duallys were 1 tons. And when you change your hydroboost. Wait to take core in until you put new one on. There is a round spring clip that you need off old one its where rod that connects to brake pedal. Just compare new to your old one and take what new doesn't have off old one. Just get hydro boost and master cylinder for 83 dually and you will be fine.

[hwh]

If you shop at Napa hydroboost part number is nbb-527307. And for master cylinder shows 4 different ones depends on 4 numbers stamped on master cylinder and if rear brakes or 13 inch brakes or not. Hope this helps a little.

[Irish_Alley]

take a look here
http://forum.73-87chevytrucks.com/smforum/index.php?topic=28592.0

youll find the hydro boost from >8400 lbs is all the same. which would all be the JD7

[Artezio]

Ok thanks for all the info, it turns out it's a 1-ton frame, on a sidenote would this truck be ok to tow a 2000 lb. trailer? It has a banks turbo with the th400 transmission and a gearvendor auxilary OD transmission. I already know to watch the egt's I heard this engine can't handle over 1000 egt temp since it wasn't built to have a turbo, though I am currently having the engine rebuilt with coated pistons

[Irish_Alley]

i know with my 1 ton truck my gvw was 12800 with a trailer full of junk. my trucks curb weight is about 7.5k. so 2k you wont see any issue, you could tow a truck and you would still be ok

[Artezio]

Cool thanks. I want to put a 3000 rpm governed on along with a tachometer since it didn't come with one but I have no idea what that requires, I'm new to this 

[Irish_Alley]

cant help you with the gov. i know on my cummins how to do it but not the 6.2 or 6.5.
the tach can be done a few ways depending on what type of sensor/tach you want to use. you can run it off the alternator which would require another device to decipher the ground signal and turn that into a usable signal for the tach or you can run a sensor off your crank and attach two magnets to it

[Irish_Alley]

heres the one for the crank sensor. i cant remember how to wire it up.
http://www.dieselpowerproducts.com/p-7611-isspro-tachometer-sensor-kit.aspx

[Artezio]

Awesome thanks for all your help Irish 

[Irish_Alley]

https://www.isspro.com/installation/IS060%20_EV%202inch%20Diesel%20Tach%20R5501,%20R5503,%20R5504,%20R5591,%20R6501,%20R6503,%20R6504,%20R6591%20revA_.pdf
theres the instructions.