how can i tell if my 1988 chevy 1500 4x4 has a single or double diaphram brake booster?the brakes are horrible.new pads and shoes and no air in the line so im thinkin the booster is bad?anybody else have brake problems?

Generally either the booster works or it doesn't, # of diaphragms doesn't matter. check the vac line to the booster, make sure it's not kinked, then run the truck for 15-20 secs, then shut it off. pull the line out of the booster at the elbow and see if it sucks air. that will tell you if the bladder is good. also check the elbow itself, i've seen these hold vacuum but the check valve is so stiff that it impedes the flow of air. suck on the hose side and if you can't breathe quickly through it, replace it. also this year may have a backfire dampener inline with the hose. replace this also. they fill up with carbon and won't flow vacuum under load. if all of this is good, check for a hissing noise at the firewall when the pedal is depressed--this indicates the booster is leaking in the valving and needs to be replaced. good luck!! db