brake pedal goes to floor and will not pump up. resovoir full. does this sound like master cylinder or booster? thanks in advance

It sounds like your master cylinder seals went bad.

I would add that now would be a good time to replace the brake fluid with a good DOT 4 fluid like Castrol LMA. That is unless you have silicone fluid in your system already. You can't mix silicone and regular brake fluid. Bleed the whole system out so you have fresh fluid at all four brakes.

Thanks for your help. going to do it thi s weekend if weather good.

probably has mostly original in it since only 76,000 miles on.

If the system is 100% original you may be in for rebuilding all the brakes soon but replacing the brake fluid every 5- 10 years will extend the system life a lot!

just bought this summer, brake shoes and pads replaced before I got it so I will have my guy check them when he rebuilds front suspension.

Have a look at the linkage. I am by no means a Corvette guy but on any car to have both plungers go bad at same time is very rare, it is redundant system in master cylinder... http://www.ecklerscorvette.com/diagram/view/index/id/139/

it seems to stop better in reverse, in drive it slowly slows down.

Oops, that diagram is clutch. My bad