Drive shaft is easily changed. Has one of the rubber boots split? But I'd suspect the dif first tbh.
Tramlining...is the car mechanically sound regarding steering and suspension? Especially the bushes. Is the set up correct? Are the tyres wearing evenly?
...is it an Elite? 
so it must be tyres then, i've put on Lasso ultra cheap winter tyres on and they don't tram line so i'll just have to live with it over the summer months, in all honesty the Falkens are not nearly as bad as the premacy's but still noticeable, atleast i can drive through the motorway roadworks with them without bouncing off the barriers ( it happened!)
the drive shaft joint i'm talking about is under the heat shield and looks a little perished, the one on the gearbox looks fine, the bushes e.tc are all good, irmscher springs with b4's polybushed, the rear tyres are wearing on the insides which is to be expected with a 30mil drop and 18" rims, not an elite, estate glx I believe? 4 wheel set up after changing the springs/shocks over.
did an oil change today and I sprayed anti rust on all the rusty bits and then over coated them so hopefully the salt will stay off the bottom of the car this year! I do have a few bits around the rear shock towers and on the front chassis rails under the abs pump which are starting to look a little serious, hopefully my treatment today will slow it down so i don't have to deal with that before i have another car on the road.