Brake systems... WTF?!

[Baralheia]

Okay, here's a doozie of a question. My truck originally came with heavy duty rear springs and heavy duty power brakes. My shop manual lists the different RPO codes for the different systems (i.e. JB1, JB3, JD5, etc), but the RPO code on my option sticker isn't in my book. What is the J55 heavy duty brake system? Would it be equivalent to the JB5 system?

From my shop manual:
System JB5 Low Drag - Front, Disc, 11.86 x 1.28 - Rear, Drum, 11.15 x 2.75 - Brake Assist, Vacuum, Dual Diaphragm

[swervin ervin]

I think code J55 just means power assisted disc brakes. Not sure on this. I do know when buying brake components, use JB5.

[ChevyTech]

J55 BRAKE SYSTEM,HEAVY DUTY

Heres a good site for looking up RPO Codes

http://www.wiu.edu/users/muwtj1/rpocodes.htm

[SanitysBane]

were are the RPO codes at?

[swervin ervin]

On the glove box sticker.

[ocbaud]

my rpo code lists j55 brakes, and i know for a fact i dont have heavy duty brakes

edit: my rpo code is j50 brakes

[Baralheia]

Thanks, ChevyTech, but that's not the information I was looking for. I know what that RPO code is for (J55 HEAVY DUTY POWER BRAKES (VAR 1)), but as J55 was not listed in my shop manual, I did not know if I needed the 2" wide or 2 3/4" wide shoes.

For the record, J55 brakes use the same rear shoes as JB5 / JD5 (11 5/32" x 2 3/4").

Thanks, swervin ervin, for your help!

[SanitysBane]

i have a question, on my 83 i have an RP0 code of F51, with Heavy Duty Shock ABS next to it, couldn't find it on the website, any clue what is it?

[SanitysBane]

ah i found it, its for heavy duty shocks, yet everything else on my truck is light duty