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If it is an inboard powerplant and your gear selection is Forward Neutral Reverse, then the symptoms indicate that this is a Borg Warner Velvet Drive transmission. Look at the linkage connection. It is located along the midsection area of the transmission backbone. This is an area that runs along a raised ridge at the top of the transmission. If this is indeed a Velvet Drive, it is known for the valve body to stick due to metal chips lodging against the spool assembly. This in turns jams the spool in its bore and since the throttle linkage plate is attached to this spool via a nut and lock washer, you will be at the mercy of these metal chips.What to do:Diameterically opposite of the selector plate/linkage, you will find a triangle shaped cover plate. Grab a 3/8 wrench and remove all 3 bolts on the triangle cover. Next, grab a 1/2 inch wrench and remove the shift linkage plate. The detent ball will drop out of place and land on the floor. No problem to reinstall. Lay the linkage plate and detent ball aside and then gently tap the shift spool out of the transmission housing. Once removed, smooth the case bore with sand paper. Then with snap ring pliers remove the snap ring from the shift spool and its retainer plug. Slide out the spool valve from the hollow interior of the shift spool. Remove the coil spring as well. Buff the outer spool with fine sand paper until it will fit the transmission bore and rotate without resistance. Next clean the spool in gasoline or mineral spirits and let dry. Do not use a rag to dry these parts as they will leave behind rag lint! Use compressed air or allow it to dry naturally in sunlight. Next polish the spool bore and spool valve together using comet cleanser as a lapping compound. Dip both parts in cool water as a lubricant while sprinkling comet cleanser lightly over spool valve. Gently seat valve into spool bore and work the parts back and forth to refinish factory valve action. Work valve back and forth in bore until it has a smooth action about it. Then rinse well in water and allow to dry completely. Once dry, the spool should fall into bore and seat itself under it own weight! If not, re-lap the part as before using cleanser and water. Once the dry fit passed the valve drop test, then refit the spool bore with spring and spool valve. Re-install the retaining plate and snap ring. Re-install valve assembly into transmission case bore and secure with triangle plate and three screws. Reattach shift select plate and detent ball.These transmissions are a piece of cake to rebuild. More often all that is needed is a thirty dollar paper and rubber kit to overhaul. Kits are available at Ford Truck dealerships and the service parts counter. The name once again is Velvet Drive by Borg Warner. Front pumps on these transmissions have an arrow embossed on them at the 12 o clock position. Make note of this when removing the 4 bolts holding this pump, because rotating this pump 180 degrees will change the pump rotation to the opposite direction! Other than this ... rebuilding this transmission only require "memory" and basic hand tools. If you can remember how you dissassembled it, reassembling it back (replacing seals) as you go is all it takes to be successful. Beats paying a couple thousand bucks for a rebuild transmission.Good luck Tom