SN: 15385T, This is a 1976 S series lathe, the "T" in the serial number is for 13-inch.
N-K-R-T-F-H
9(N)-10K(K)-10L&R(R)-13L&R(T)-14-1/2(F)-16(H)
The T series lathes had the older total loss top-oiling headstock.
"Does anyone know the correct size oilers for the gear box? mine are completely smashed in there and I'd love to buy some new ones to replace them with before I pull them out."
SBL-155x20
Gits 501 - Beaded Drive in, Style G – Steel, Trivalent Zinc Plating
--Drive-In Hole Diameter--Drive Diameter--Drive Length--Overall Height--Assembly Clearance--Item #
--------------------------------Min--Max--
----------1/4------------------.253--.255--------5/32-----------13/32----------------11/16----------00501
Steve