The bridge is from GFS.....guitar fetish.....called large mass or something. Easy to string....lots of saddle adjustments.
It is called oversized top mount bass bridge in chrome.....current $20.95 (us) plus postage.
http://www.guitarfetish.com/Oversize...ome_p_578.html
Thanks Ozzie, I will keep that in mind when building a 4 string F style Bass in the future. Looks like it would be OK on the PBG RC4 too.