Just recently I fitted one piece polybush's to a mk4 and I had everything ready to use to "press" the new bush in the axle but honestly after cleaning the inside of the axle an applied copper grease the polybush literally pushed with very little resistance, it came with a solid metal piece that goes straight through the polybush that crushes the polybush tight into the axle. This was tapped in using a hammer.
I suppose it all boils down to what you buy and where you buy it from really as with everything you buy these days. Sometimes the saying right you get what you pay for.
But what dave have said is right its what set up you want as everyone is different.
Yeah I ended up pressing mine in, 10ton..
As you say all items are different, and tolerances in the beam could even be different.
My experience was a ball ache, which ended up removing the whole rear beam.
They were cheap and maybe this was the sacrifice I made.
Certainly don't let me put you off, poly bushes are great at what they do, just sometimes too good.
