Wishbone Classics only stocks and sells original style Tri-Metal construction main bearings for Triumph GT6, TR250 and TR6 engines.  Tri-Metal bearing construction consists of a lead copper bearing base which can withstand high loads.  The over-plate layer (thin top coat) is a lead copper tin material. 
Additional durability and performance can be obtained by selecting our performance coating option.  The coating is a very thin sprayed application of a moly based material which has exceptional film strength and reduced surface friction.  The structure of the dried moly film is semi-porous and will hold oil on its surface.  The coating film reduces wear in low oil situations, such as engine start-up or in the event of a lubrication system failure on a race engine.
This bearing set is as close to the original Vandervell bearings as is available.  We have had nothing but success running these in the engines we build for our customers. 
NOTE: We strongly recommend you purchase and measure your engine bearings prior to determining the final size of your journals.