If anyone is interested in making an alignment gage very similar to the Doby Gage shown above, made one about (3) years ago (1) as follows:
1. Main Horizontal Alignment PVC Strut: Cut a piece of 3/4" PVC pipe approximately 47" long.
2. Hidden Inner Spring: From a hardware store, get an approximately 3/4" diameter coil spring approximately 6" long. (Bring a piece of 3/4" PVC pipe to store to make sure spring fits & slides easily).
3.. Left & Right Wood Dowel Pin Holders:
A. Fixed End: Cut a wood 3/4" O.D. dowel approximately 34" long, insert wood dowel in fixed end of PVC pipe allowing 1-1/4" of the dowel to protrude on the out-side of the PVC pipe; then secure this approximately 34" long dowel in a fixed position with a 1/8" through bolt provided at approximately 2-1/2" from the fixed end of the PVC pipe.
B. Sliding End:
a. Sliding Wood Dowel: Cut a wood "sanded or shaved" 3/4" O.D. sliding dowel, (to slide easily inside the 3/4" PVC pipe), approximately 12" long, & with a Dremel tool, cut an approximately 4" long x 1/8" (+) wide slot in the longitudinal center of the dowel.
b. Insert the coil spring into the open end of the PVC pipe allowing it to rest on the inner, fixed 34"long dowel.
c. Drill a 1/8" centered hole through the PVC pipe, approximately 6" from the sliding end of the PVC pipe.
d. Provide a 1/8" through bolt through the PVC pipe & through the slot in the wood dowel so the slot acts as stops to prevent the dowel from sliding out of the PVC pipe, & from compressing the spring too far.
C. Steel End Pins: Drill an approximately 1-3/4" deep hole in the centered ends of both dowels. Cut (2) 12 penny, (12d) nails approximately 2-1/4" long & insert in the drilled holes in both ends of both wood dowels & allow approximately 1/2" of the steel pins to protrude outwards from outer ends of both wood dowels. With a file, provide slightly rounded smooth pin ends where end pins, (nails), will contact front tires.
(NOTE: All dimensions above will depend on the "trial & error" exact lengths of the spring, dowels, & locations of through bolts -- if doubtful, not a bad idea to get (2) dowels, one for trial, one for final. Nicer to provide bullet shapes on ends of both dowels so one can better see the position of the pins on the front tires.)
D. Provide & secure small chains on each end, dangling 6" from center of PVC strut to bottom end touching floor.
E. Wrap masking tape on sliding wood dowel, place tool on engine side & between front tires. With 6" suspended chains touching floor, mark tape at outer end of PVC pipe strut with a fine point black pencil. Roll car backwards approximately 36" until ends of suspended 6" chains contact floor again, & again mark taped wood dowel at end of PVC pipe with a fine point red pencil.
F. Remove tool to see toe-in dimension between red & black pencil mark.
. the tubes on the market leak, so if you go that route buy them from Brattons... he has them specially made to spec and is the only one selling them to my knowledge..