R 3500 P/U 2WD V8-454 7.4L VIN W 4-bbl (1988)
FIGURE 2
DATE OF PRODUCTION CHANGE:
By October 6, 1986 (Julian Date 279) (Figure No. 2) all 1987 THM 700-R4 transmissions were produced with an auxiliary valve body for an improved
drive engagement shift feel. As part of this change, the lo and reverse #5 checkball located in the valve body assembly (Figure No. 3) was eliminated,
and a new forward clutch checkball (#12-Figure No. 1) was added to the Auxiliary Valve Body. All 1987 Service Replacement Transmission Assembly
(SRTA) units have this change.
FIGURE 1 - CHECKBALL LOCATIONS ON TRANSMISSIONS WITH AUXILIARY VALVE BODIES
NOTICE:
1987 Service Manuals refer to the forward clutch checkball (#55B) in the auxiliary valve body as #5. To avoid confusion with the lo and reverse #5
checkball in a THM 700-R4 transmission produced without an auxiliary valve body (#55B-Figure No. 3), the forward clutch checkball has been changed
to #12 (#55B-Figure No. 1).