There appears to be a few extra threads on the shaftec piece,but in what way would this compress/load the CV joint?
The critical length is between the gearbox & the hub/wheel bearings.
Was the Ebay listing a private or business listing?Have you a record of the item number?
Too my eye,judging by the extension of the CV boot,the shaft is too short & is probably a non cup PH2 R218AL thrown into a correctly numbered box.
I do not have a personal axe to grind,other than that ill informed comments nearly swerved me to paying more than twice the price of the R218AR that`s doing perfect service on my non cup 172 PH2.
If Cup shafts are NLA from Renault,& K-Tech are £249 a side for Cups,then I feel that is it appropriate that there should be some feedback from someone that has purchased Shaftech from a reputable source.