I´ve got a 1968 Delmont 88 Convertible with a 2bbl 455 and a 3-speed manual transmisson, column shift.

What gearbox is this? Heard someone say that it could be a Ford Toploader?

This is an original car, matching numbers, nothing changed.

Im thinking of getting a 4 speed installed and it would help to know what the original gearbox is.

 

Good god, that's a rare beast. Yes, that is a Ford 3-speed in there. When you remove it and clean it off you will find "Fomoco" cast right on it. I've pulled stick setups from a few full-sizes over the years and that trans was used in at least 1965 through 1970. I did, however, find a 330-powered '65 Jestar 88 with the lighter duty Saginaw 3-speed.

 

The HD 3 speed, Ford top loader, is named because of the stamped steel top cover plate instead of the side cover with shift levers of the Saginaw/GM unit. The Ford was used from 66-71, and was standard in big cars and 442s during the time period that it was used.
The Ford was very strong, and indeed the top loader 4 speed was tested by Olds engineers and they wanted to use it in 442s, but were stopped by GM management. The Ford designed and built trannies were the strongest and best shifting in their era. Today's Jerico that the NHRA stock and super stock racers use is based on the Ford design.

The ratios of your tranny are 2.42, 1.61, 1.0 forward and 2.33:1 reverse.

 

Thank you so much for this info guys!!

I wonder how many Delmont Convertible with 455 and 3-speed manual that was built? Must be quite rare.

What is the final gear ratio of my 12-bolt LSD rear axle - any info about that?

Is the 4-speed toploader 1:1 in 4:th gear or is it "OD"?

 

4 speed top loaders can have long or short inputs, 2.32 or 2.78 first, all are 1:1 fourth, unless Ford made some ODs in the late 70s, 80s or something. Most big blocks used 2.32, 1.375 x 10 spline short inputs. The only 2.78s would be the 1.06 x 10 spline.

 

Since I'm not a Ford guy, I can't say whether the 3-speed toploader in the Delmont has a unique input spline pattern and length to fit in the Olds or also whether it has the same front bolt pattern as a 3-speed found in an actual Ford. If you are going to do a 4-speed conversion, the easiest is to use a long tailshaft Muncie 4-speed. Olds used them in 1965 and 1966 on their full-sizes and they were used more commonly on full-size Pontiacs 1965-1968. Your bellhousing should have 2 bolt patterns on it - one for the Ford toploader and one to accept a Muncie (actually it will also accept a Saginaw 4-speed but there is no long tailshaft version of that trans). Using the long tailshaft Muncie 4-speed allows you to use the existing driveshaft and clutch/pressure plate assembly.

 

The Ford 3 speeds in GM (Olds and Pontiac applications) used the GM 1.125 x 10 input, with the Ford output spline and a special yoke that took Olds (big Saginaw) u-joints.

 

Thanks for this information!