Lotus 51a FF U-Joints

[ROCKNEY@inetpop.is.ge.com (VAUGHN ROCKNEY)]

I need a pair of new outside U-joints for the original stock half-shafts 
for a Lotus 51a FF.  It has the rubber doughnut type inner joints and 
the stock Renault gearbox.  The old U-joints are missing, and I don't 
have a part number to go by.  Does anyone on the list know if these 
joints are a common size, and if so, what, and if not, is there a Lotus
source for them?  Thanks in advance.
Vaughn Rockney