1995 Chevrolet Silverado Shifting Problems

Are you stating clutch pedal is spongy. Can you provide a little more details

Try to describe the best you can. Is it in the shift lever when you select a gear or does it slip when you let go of clutch after selecting next gear?

Ok since the concern is with the shifter and no grinding is heard indicating worn synchronizers in trans I would first check the shifter to make sure it was properly tightened to transmission after last repair. Will cause excessive play in shifter affecting every gear. If no issues are found with lever you will have to take off top of trans where shifter goes in and inspect for wear in the ball.

Remove shift lever boot on bottom, should have screws or bolts to take out of floor once that is out you can access to bolts to remove the shifter. Make sure when shifter is put back in vehicle that it is properly lined up and shifts every gear before reinstalling boot.