I was wondering if someone met 66 Riv with 2,78 posi? And if anybody knows of that thing existing i would be interested in buying that.
I believe Erik is correct. If you really want a high rear gear, and you can't find one, you could run a taller rear tire. Just throwing that out there.
The posi I had out of the '66 Riviera I owned was a 3.07. I sold the internals a few years ago, but still have the housing with the ratio ID stamped in it. I don't recall what the code was off the top of my head, but could check. The '66 Buick service manual listed that code as being a 3.07 ratio. o No:
Good question. 3.07 was standard in the Riv which carried a code stamp of PJ or PM (open or limited slip) 3.42 was standard in the GS which was Code PY. This could be ordered in non-GS cars as well. There is a 2.78 posi listed in the shop manual for the Riv which has a code of PR for the posi. PK is for the open 2.78 differential. We know the shop manuals are not error free. I have never heard of the 2.78 going into a Riv but that doesn't mean it never happened on a special order and in reality it probably did however it would be very rare. I'm going to dig a little deeper on this. Regardless, if you are planning on locating a 2.78 carrier it will be extremely difficult because it would have been special order and its not something the dealer would recommend for the bulk of their buyers. I should mention the manual also lists a 3.23 ratio available as a posi only with a PN code stamp.
I have PJ stamped on rear.I am considering 2,78 becouse i mostly drive on longer distances and was thinkin that highway ratio would be better for me.I dont race that car,maybe sometimes a little burnout(thats why i asked about posi:3gears: ).If i cant find 2,78 wich is stamped PR i am goin to find 3,07. Maybe someone wants to get rid of 3,07 than?
Thats interesting couse my Riviera has 15:1 steering,HD suspension,cast covers,chrom air filter and that little GS ornament below glove box,but dont have 3,42 and fender emblems,and there is no holes to mount them and there never was any hole....
I hate the 3.42 in the GS cars because most of my driving is to and from meets mostly on the highway. They do rip out of ther hole though for a big car. The 3.07s are great highway gears on the Riv. Not bad acceleration either because of the switch pitch converter. Considering my experiences running 3.07s and 3.42s I wouldn't want 2.78s unless you frequently need to run 80mph plus for extended periods. I have for sale a nice complete 3.07 limited slip/posi differential from a 66 Riv. $200 plus shipping.....which might be killer. :ball: Anyway, let me know if interested and I can send pics and get shipping cost.
C'mon gang. Bolt the damn 3.42 in and for highway cruising bolt on some really tall tires. My highway tires drop the RPMs 500 at cruising speed. When I arrive at the destination I simply bolt on street slicks.
