Normally you can output the set within the proc function with the output out=p p=yhat (p is an arbitrary designation) statement with the predicted values by using the p=yhat . From there, you can transpose the set and use the functions min,max, etc...
See code below.
If there are more efficent methods I would be game to hear them. Hope this helps you.
proc transpose data=X1 out=descstats;