I know that the mid to late 70's Dodge truckes used a saginaw box with the coupler, maybe you can find one of those to work. I remember rebuilding mine several times years ago. Tim

1941 Taylorcraft
1968 Charger
1994 Wrangler
1998 Wrangler
2008 Kia Rio
2017 Jetta

I didn't do 4 years and 9 months of Graduate School to be called Mister!