[750hp]

Thanks a million for all responses - there's so much good information here that I'll try to summarise everything into one response.

The Arntz is my old workhorse and is the car I currently drive to work everyday. The current mild motor and 4 speed and 3.54LSD Jag IRS have been a cheap, reliable and fun combination for the time I've owned the car. I bought a more radical and all round "nicer" and more authentic looking 427FE Contemporary with the idea of selling the Arntz, but the attachment is too great and I couldn't bring myself to sell it.

The Jag rear in the Arntz needs replacement radius rods as the bushed rod end at the hub end developed a crack at the mounting point. With some general creaks and groans that come with the fact that the rear end has even in the car for over 30 years, I need to look forward towards to an impending engine change, and get the rear end ready. I want to continue to drive the car every day with the new mechanicals. Other than the usual car required with a solid roller cam, the rest of the engine is relatively low maintenance. I only say this so that I don't give the impression that I'm turning the car into a single purpose drag car. That won't be further from the reality.

The motor is a 398 cubic inch small block Ford with a YS Vortech (DV, this is the same motor that OZVENOM and I were installing into a previous Cobra way back when we met you for the Fling back in 2002). I'd like to use a tweaked TKO600 with a sprung hub clutch assembly, and hoped the custom Jag rear would solve the rear end requirement to upgrade or rebuild. The idea of having to replace both the inner and outer stubs, plus then install or of Mickmate's great Watts Linkage systems, then replace what I already believe to be an unsuitable center section, well that's all getting a bit expensive with the ongoing uncertainty about the half shafts, unis and who knows what else.

If I was to consider a quick change "live" rear I'd be inclined instead to use what has worked for me in the past and that I have a lot of spare parts for; a 35 spline, 4 link 9" with 1350 unis to never have to consider parts breakage again. Perhaps with a Mumford Bar locating arrangement. I hate the idea of potentially sacrificing ride quality to retrofit a live axle to an IRS car. Nobody but my Dad and I and handful of passionate Cobra enthusiasts even really know what an Arntz is over here, so resale value of any mods isn't a consideration. The main issue will be the drastic engine setback in the Arntz and a live rear end would possibly lead to the worlds shortest driveshaft and uni joints that bind at full suspension travel.

Patrick, thanks for DCDoug's repair thread. I think that single handedly turned me off the idea of trying to work with what I have!