Well sorry but it not not lock in 4WD it increases the RWD by some amount but not 50/50 f/r. It's only functional when the selector is in 2nd or 3rd. When it's in 2nd it stays in 2nd and when it's in 3rd it will pick 2nd or 3rd. I use it in 2nd for stop and go.
This is another neat feature. With the gear selector in 1st, the engine can be floored and the transmission will shift to the next gear when the engine reaches red line.
So there is a good chance that a used SVX has not been over the red line.
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May your transmission live forever.
SuperbVehicleXtraordinary
Proud sponsor of a 1992 SVX.
