Anyone using a Gear Venders O/D unit?
To calculate the new gear ratio simply multiply your rear end ratio by .78 to get the new final drive ratio.
4.10 X .78 = 3.20 Final Drive Ratio
4.30 X .78 = 3.35 Final Drive Ratio
I have a Gear Vendors unit on the shelf for my build, so I can't vouch for it yet. But I do think they are an excellent product, they warranty the item to 1200 HP. So you know it should handle most big blocks and small blocks without breaking a sweat.
As far as fitting, according to their website, installation requires only a couple of dimples from a ball-pean hammer.
Regards,
Joe Dokes