Quick view Add to Cart Vultee - Installation of An Improved Battery Sump and Venting System - BT-13, BT-13A, and BT-15 [feb3bt13csc34] Document Part Number: T.O. No. 01-50B-70A Number of pages: 2Part Number: T.O. No. 01-50B-70ARevision Date: 16-May-1944 MSRP: Was: Now: $15.00