Turbo shaft play

[Cakes]

Today while adjusting my turbo hoses I moved the turbo shaft and it went in and out about 1/8 inch total in the thrust direction. I know that a minuimum of movement is accetable(just like crankshaft). I have been having a knocking problem when engine is warm(from around 1500-2500 rpm) I dont think this could be the problem since the sound is very rhythmic and I would think if it were the shaft it would not be rhythmic. Anways....it lookes like the turbo needs to be rebuilt. Does anyone have any ideas what it would cost for a full rebuild? Should I do any upgrades? (i.e. New/different turbine wheel or new/different exhaust wheel....mods are listed below) Thanks!

 

[turbo buicks]

i had 1/8" in/out play in my 49 once. $550 later, no play. only thing saved were the compressor/exhaust housings. the guy said if i had any up and down play it would have hit the back of the wheel on the turbine housing and blew apart. glad it wore evenly