The GA 31/2 Precision lathe was built very much along the lines of the GA 21/2 but with an increased centre height, stiffer tailstock, much heavier compound slide rest (with a 5.5" travel top slide) and the option of flat instead of round-belt drive. The machine was built in just one version - with a centre height of 3.5" and a bed 32" long which gave a capacity of 18" between centres.
The 9/16" bore headstock spindle, with a 1.25" x 10 tpi nose,  accepted GA 15 mm shank Size C collets (with a maximum bore of 3/8") and was hardened and ground - and ran in hardened, ground and lapped steel bearings.
Both headstock and tailstock accepted the same half-length No. 1 Morse taper centres as used on the GA 21/2 lathe. The bed was formed with one raised V and one flat - the same V locating both the slide rest and the tailstock.