A good core is worth $150 Another thing to keep in mind is the early 80 -85 not exact on the year had no fail safe.What I mean by fail safe is ,if the throttle valve cable is not set correctly or breaks you loose all pump pressure.What GM did was add a fail safe so if this did happen it boosts the pump pressure preventing it to shift but does'nt fry the unit from low pressure.The 88^ have better internal parts .The out put shell has a high failure rate , they strip the centers out.
By chance either of these cores 4WD units ? I'm looking for one.
