Tensioner Bearing

[squealingtires]

'74 Fiat Spider 1800 engine. I bought some parts from International Auto Parts in Charlottesville, VA a few years back and now I'm just getting around to installing the parts. Anyways, the guy at the counter sent me away with the bearing on the left and it's different than what I just pulled off the car Arrrggg! The outer bearing diameter is probably 2mm larger than the old bearing and the inner diameter is the same. I think I can live with the 2mm however the fillet on the inner diameter has me concerned because the retaining washer doesn't seat properly with the larger radius fillet than the original. I know that the retaining nut doesn't do much due to the tensioner shaft holding the bearing square but would it be best if I ordered another bearing? Also, the older bearing has a two piece inner race and two stacks of bearings. Is this the better design of the two shown?

[So Cal Mark]

sounds like you got a 2L bearing