When rebuilding a 36-year old Land Rover...

...a reliable source of bolts can help.

Here is the Bolt Depot, replete with really smooth-working online shopping cart system. Nice, informative visual catalog and the widest selection of fasteners I have found.

And there's this...

Guide for Specification of Imperial Socket Head Cap Bolts

...which should be laminated and stuck on the wall of the shop of any self respecting auto-restorer. Like..."Where is the Bolt Guide when I'm in a pinch?"