Hello,

If the car originally came with a M41, it would have come with a 4:56 rear end ratio inside of a Dana 30.

Dana 30 rear end gears are available and I think there is at least 1 aftermarket manufacturer, but I would only use original Dana ring and pinions.

You can go as far as 3:73 without needing to change the carrier housing, but I would recommend going to 4:10 or 3:90.

You will be a little sluggish on the take offs, but if your goal is to cruise on the freeway without having to spin high rpms, you will be happy.

Your speedometer will not be accurate, but if you want to spend the money that can be fixed.

We just installed a rebuilt Dana 27 with 3:73 in a 58 444 along with a completely rebuilt B16.

I wanted to get 3:90's, but after waiting for over 4 months without success in locating a set, the owner insisted that I install the 3:73 set that I found even though I have a 4:10 set in stock.

The customer really wanted a freeway gear.

Even though it was a little sluggish off the line, I was surprised at how well it handled freeway speeds and it cruised quite comfortably at 75mph according to the GPS I brought with me on the test drive.

--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502