OK, here are your 727 extension housing seals. The most common one>>>2.503" can come with or without the rubber boot. Most transmission shops used the non booted one, and in our Overhaul Gasket and seal kits, the non booted one was put in. Used from 1965-on. However, there are 2 not so common ones>>> 2.445" OD used with the bolt on yoke. Used from 1962-on, and the other one 2.847" OD, used on trucks with the bolt on yoke from 1987-on. Measure the OD of your seal and go from there. Again, should be a non-issue finding one. Hope this helps.