Well I'd send them back! Mulfab are the people who designed them and yes you'll pay top dollar but they'll be right and the service is great. I have seen quite a few variants on a theme and the lengths seem to very as well, some are not even drilled! This can cause rubbing issues if the length is incorrect! The slotted version might be to build in a safety factor as a weak point in case of accident damage to the chassis, ie. a predictable failure point but rather I think as for ease of fitting ..... not having to remove the oiler bolt.
Back to failure points though! some years ago the chassis connection bolts were made from a soft mild steel for the purpose of failing under such circumstances but I notice now that they are being supplied with high tensile steel bolts. I have been experimenting with brass 1/4" fastenings at the chassis end in order to reinstate this failure point to protect the chassis. Installed now over a year ago they are working well although I don't feel I have covered enough miles yet to fully asses their functionality. But in saying that it is my intension to change them out as a service item on an annual basis.
Again "P" look up my posts on BRB fitting and I have fully explained how to do the job! So to round things up! buy from either Mulfab, Wolf performance or Williams if you want the correct item. It's the top of the crosshead you are stabilizing and you want it to fit properly at it's point of origin namely the top of the fixed pin! It works in both planes in that it's a tie rod and a brace so carries load forces in both directions!
