If you look
here you should be able to work out which camera you have, assuming that it has a screw mount lens. They have another page for bayonet mount bodies, if you mean that it's an MG. Sad to say MGs are not worth much even in black, although if it's working and the viewfinder surround isn't cracked it's a step up from most of the ones on ebay!
Pentax offered pretty much everything in black, but with most of the older bodies it was an optional extra for which you'd have paid more and waited longer. AFAIK the following were black as standard, there was a chrome option on some of them:
ES (and the short-lived "Electro Spotmatic" which came before it)
ESII (could be had in chrome)
MV
MV1 (also exists in chrome)
Super A/Program A (I think the version badged as the "Program Plus" was offered in chrome?)
A3/A3000
All the P3s/P30s and the P50 were in black or dark grey
The LX was launched in black but has also appeared in titanium silver, there was a gold plated limited edition too
That accounts for the manual focus bodies, unless I've missed some?