I never thought at my age I would be a newbie ,but OK, kinda like it !

 

Welcome, tell us a bit more about yourself, car, etc...

 

I own an auto upholstery shop in S. Daytona . I have owned a handful of Olds over the years currently have 72 conv. With a 350 / 350 trans / 10 bolt switching to 455/400 /12 bolt

 

Welcome to the site. Always nice to have an experienced upholsterer to maybe answer questions later on.

 

Welcome.

Which "12 bolt". Most people don't realize that the Type O axle used in the 1966-1970 Cutlass line isn't a real 12 bolt, despite the number of bolts on the cover. A Chevy 12 bolt has 12 bolts holding the 8.875" ring gear. The Type O "12 bolt" only has ten bolts holding an 8.5" ring gear, same as your current 10 bolt (though parts don't interchange between them). Be aware of this when sourcing your 12 bolt axle.

 

Questions are welcomed....I grew up working on these cars and convertible tops !

 

Didn't know that about the Olds 12 bolt .....thanks ....I have questions about headers to fit 72 442 conv. with 455 ?

 

Welcome to the site. Post pics when you get a chance.

 

Welcome aboard.

 

Yes quality headers fit no problem. Do not believe the catalogs that say wont fit conv!

 

^^^THIS! There is no difference in header fitment from a convert to a Supreme to a Cutlass to a 442 of the same year range. The issues you will have are common to all. The first is that every header manufacturer routes the tubes differently, so a given set of headers may or may not clear the backdrive linkage from the trans to the steering column. This is needed not only to lock the shifter with the key but also to operate the backup light/NSS switch that is at the base of the column, even on floor shifted cars. The second issue is that header manufacturers seem to have crappy repeatability as far as consistently shaping pipes from one set of headers to the next, so don't be surprise if there are places where the headers are close or rubbing. This is unfortunately a fact of life and has nothing to do with body style.