Brake Identification?

[Young Truck]

I recently inherited an old 86 c10 that I'd like to fix up to a more drive-able state. I don't have access to the truck right now so I was hoping someone might be able to help me out in identifying my brake system, or am I just SOL? I saw a recent thread about the J55 brake code, as you can see below mine is similar with only a J50 brake code. I'm not certain what my max GVWR is and that seems to be the final piece I'd need to know as far as I can tell. I've been trying to figure this out for a few days without any luck.

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My second question is, if I'm changing out everything, wheel cylinder, shoes, and drums, does it matter what the original size was as long as I get all the same size for the new ones? As far as I saw, the front rotors will have a different spindle between the two, is that correct? Thanks in advance!

 

[Young Truck]

So I was able to have someone take a picture of the GVWR sticker for me, apparently it is 5200. So looking at some of these other threads, would that mean I've got the JB3 system?

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[Keith Seymore]

I'm sorry- I don't see a 5200 lb GVW on the chart.

I checked all the way from 87 back to 81 and the all are either 4900 lbs or 5600 lbs.

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[Young Truck]

Interesting, I'm seeing it as an option on the GM heritage center page below here, but supposedly if I have a 5.0L the only option is for the truck to be a 6100 GVWR according to that, unless I'm reading it wrong. Guess I'll just have to wait to get my hands back on it and measure whats there! Thanks for the info.

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[RoryH19]

For the rears, I would also verify the backing plate is the same for 2" vs 2.75"

Are you sure the truck is an 86 not 87? The reason I ask, is that I was rather sure the 700r4 (4 speed auto) didn't start until 87.
At least for 2wd. I could be mistaken.

k5 started in 82 for sure.

 

[Turbo4whl]

For the rears, I would also verify the backing plate is the same for 2" vs 2.75"

Are you sure the truck is an 86 not 87? The reason I ask, is that I was rather sure the 700r4 (4 speed auto) didn't start until 87.
At least for 2wd. I could be mistaken.

k5 started in 82 for sure.

The 700R4 was first offered as a option for a two wheel drive in 1982. Not as many that were ordered by dealers for, gasoline engines, were actually received in early 1982. This is because the 700R4 was the only trans offered in the new 6.2 diesel. GM was looking at fuel mileage numbers and wanted to make sure there was a trans available for every new diesel.