1998 Chevy Astro front axle noise and vibration

My 98 astro awd has an intermittent shudder like driving over rumble strips at a turnpike exit alert and a whine or growl like mud grips on pavement(pass. side). when van shudders,I tap on brake lightly and shudder stops. I already paid to have the c-v joint,hub,bearing where drive shaft goes into front pumpkin replaced.I found axle rod had slipped out of placein pumpkin and into c-v and damaged splines.he dressed splines and reversed shaft.paid "mechanic" over 1000.00 for several wrong guesses at the problem.I can't send a donation right now,I will definitely be able to do so as soon as I fix the van and my money isn't the retirement fund for "mr wrong wrench".Can you please give me a clue as to where to start,My son has mechanic training but no drive train exp.He will be doing the work.PLEASE HELP!