3281 is the P/N for the tie rod. B-3281 was A-3281 just the part number changed 28-34
On the tie rod ends they had threaded grease fittings until about Sept 1930 & the fitting faced toward the front (fitting and clamp bolt were on different sides of the tie rod end) about Nov 1930 the grease fitting were press in and the clamp bolt and grease fittings were on the same side. Form 32-34 both the clamp bolt and the grease fittings were on the same side (rearward) and the grease fitting was threaded Zerk type.