.125UNF x 1.250 long Bolt has many areas found on the car.  Cloud I & S1 - Exhaust Manifold to Downpipe (3 bolts per manifold); Center, Front Silencer & Tail Pipe Silencer (6 bolts)...

This is the exhaust valve. Old part# UE41083 & UE72837 1979-1980 (38972-41686)1981-1994 (1001 to 46740)  

This is the main spring for the inlet and exhaust valves on all cars from 1960 to 1969 and on the inlet valve only from 1969 to 1986 except Turbo models. 1960-1969 Silver Cloud II, III &...