Does the spline on a mopar 727 904 or 999 make difference when swapping transmissions 1982 dodge d150 can I just pull any tranny from junkyard and use it if its 999?

Yes, the spline count on the transmission input shaft does make a difference when swapping transmissions. The spline count refers to the number of splines on the input shaft of the transmission, and it must match the spline count on the transmission extension housing of the engine.

If you have a 1982 Dodge D150 with a 999 transmission, you will need to find a replacement transmission that also has a 999 spline count. If you install a transmission with a different spline count, it will not fit properly and will not be able to engage the engine properly.

Therefore, it is important to ensure that the replacement transmission you choose has the same spline count as the original transmission in order to ensure a proper fit and functionality.