I've an NP420 sitting in my backyard.

It's a cast iron granny low 4 speed with no synchro in Second (or First) gear.

It needs a 5.125" hole to fit into.

The bolt pattern is two on each side, one pair on top and one pair in the middle. The passenger side lower hole is a little farther out from center.

Look it up online, it has a pretty low First. I don't like it because Third is in the 1.7 range so shifting down going up a hill puts the engine into "screaming" mode.

The bellhousing between the 420 and my Poly 318 is 8 3/16" deep, face-to-face. It has about a million holes in the block side, supposed to bolt up to flathead 6, A/LA engine, possibly the slant 6 as well.

The hydraulic clutch uses a slave cylinder bolted to the passenger side of the bellhousing. It is a very simple setup, no mechanical linkage to get messed up. The master cylinder is the same as the brake M/C on the older Sweptlines.

If I can figure out how to get pictures off my iphone, I'll post some.

One thing for sure, the NP420 isn't a high dollar transmission, but it is pretty stout.

R.

See also, http://www.sweptline.org/forums/viewtopic.php?f=19&t=11856&p=80934