when ever i needed a prop when i was fitting i always used the extended one or two for me i converted a 4x2 tractor to a mid lift and needed a longer prop
http://driveline-hydraulic.co.uk/?Propshafts
good bunch of lads
i couldnt comment if they do kit car prop but mayby worth a look
they are based on white lund ind est 20 mins of junc 33 of m6
jay