I think I know what he is talking about. I just picked up some 12mm x 1. 5 x 6AN fittings. The inside of the fitting is kind of necked down. I have a set of letter drills that i will be checking tomorrow to see what size to ream it out to. The fitting is solid alumionum, so I will be hogging it out a little.
Oh yeah, If you buy Aeroquip fittings, make sure the proper ones are in the box. It seems that part number FCM2246 has some 14mm x 1. 5 packaged in them. The local place I buy fittings has had to order 12 fittings so that I could get 4 of the REAL FCM2246