I didn't check the Serial as slej already has, but that is a "Pre-Fender" Guild. Not to be confused with a "Fender Guild". A pre-fender Guild will have and retain quite a bit more value than a later Fender made Guild.
I have a 78 F212 SB which I dearly love.
As for a crack in the bridge, take a good close look at the top between the pick guard and the bridge. Look for hair-line cracks. Those old pick guards were seriously glued down. As the p/guard ages it shinks. You may even see pick guard curl around the edges of the pick guard. The shrinkage could possibly cause a hair-line crack from beneath the pick guard to the bridge.
http://www.frets.com/FRETSPages/Luth...lueguard1.html
Les