Black Acetal Delrin nut block 3/8-8 acme thread, FAST, right hand, four start.  Made in USA.
The nut block has 1/4-20 x 3/4 deep mounting holes in 4 places. This allows for 1/4-20 screw mount or 10-32 through hole clearance.

Overall dimensions:  1 3/8 inch wide x 5/8 inch deep x 3/4 inch high

Nut can be mounted from the top or front. Front holes clear 3/8 acme screw with
1/4-20, socket head cap screw mounting.

This design allows for very tight design for either traveling table, like a
milling machine or traveling head, like a CNC router.  Also useful for 3D printer Z-axis.

Purchase mounting hardware and lead screw separately, listing is for one delrin nut block only.