80 series drive line clunk

I have a 1996 80 series TD auto GXL which i have just installed a part time kit.
It now has the dreaded clunk like the FJ cruiser's have. As you come to a stop it clunks or if you take off it clunks. Place it in neutral when stopping and no clunk or brake very lightly to a stop and it usually won't clunk. I grease the slip joint and clunk is gone for about 3 days then gradually comes back.
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The FJ cruiser fix by toyota is to replace the drive shaft.
A local Sydney shop wants to replace the slip joint and unis for about $500. Does this sound about right to anybody whom has had this work done or does anybody have any suggestions where to get this repair done?
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I am a mechanic by trade and I'm 100% sure it is the slip joint as it does have some play in the splines. I am thinking for $500 I can almost buy a new one.
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Any suggestions would be greatly appreciated.
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Scott