u/FourEyes4456

Long story short: Mating a '70s Ford toploader 3-speed to the back of a Chevy 4L80E. No, this is not a shitpost - serious request.

Why? Two reasons:

1. I need more torque and don't want to buy a doubler
2. I found a 3-speed for $20 in damn near perfect condition

I've found absolutely nothing anywhere on the internet about anyone doing anything similar to this (gee, I wonder why) but am hoping to see if Reddit has any pointers before I start this absolute frankenstein of a build.

I may need professional help after this is done, so if somebody could direct me to the nearest psych ward to Pittsburgh that would be incredible.

I know this is a slightly unusual question, but I want external opinions before I dive way too deep into a project of mine.

I'm currently working on building an off-road recovery vehicle, I'm about a year and a half into planning and a handful of months into actually putting the thing together. I have an engine getting assembled in my garage, but I'm trying to figure out transmission and everything that goes with that at the moment.

My goal for this is simple to say, but incredibly complicated to do: and off-road recovery truck that is both entirely trail capable, and also able to be a daily driver. The daily part is what's confounding me with the doubler the most, because if this was strictly a wheeling rig it would be much less of a problem.

The current plan for driveline is a TH400 coupled to an NP205, with 4.10 geared Ford F350 axles. Doing some rough calculations - the TH400 has a first gear ratio of 2.48:1, and the NP205 has a low gear ratio of 1.96:1 - I would have a maximum low range gear ratio of about 20:1 at the wheels. What I'm not entirely sure of, though, is if I would need to go more. I'm mostly in the Northeast, so more forests and mountains than sand and cliffs.

I have a handful of ideas on how to increase the gear range, and I'm leaning towards one of these but don't want to invest dozens of hours into this abhorrent creation if it would just be a waste of my time to do so