I did mine last weekend. Here are some photos.

My advice is to find someone who has replaced a 75/ZT thermostat before. Putting in the metal thermostat is basically the same however I have a few points. 1) The old bent pipe will probably be corroded in place. Probably has to be broken and taken out in pieces. Then the holes need a very good clean/scrape and perhaps some use of wet and dry sandpaper or similar to ensure the surface is very smooth for the new O ring. Failure to do this will likely mean you waste your money. 2) Kaiser has used fat O rings and you have to be VERY careful not to pinch them when installing them. As per his instructions you need rubber grease or similar. I pinched the one for the thermostat housing but stopped before it did damage. A small mirror helps to see the back as it is inserted and I used a flat blade screwdriver to push in O ring as I pushed down. The O ring for the bent pipe wasn't as hard and the straight pipe to thermostat also has to be done carefully. 3) As per Kaiser's instructions I used jubilee clips rather than the original MGR clips. For the middle one I decided that it was best to have the screw/bolt accessed from the rear below the back pipe. So in other words, do this one first (Should be common sense for a mechanic) 4) I bought two new clips for the straight pipe rather than trying to salvage the old ones or use cable ties. I think the original clips are best as they should be rated for the heat etc. once again I think poor investment not to do this. 5) As per other comments, replace the inlet manifold gasket(s). You can see in the photo I had not yet replaced mine but I did that as the next step after the photo 6) I found taking both inlet manifolds off worthwhile. The job can be done by just taking off the front one but with both off you have clear access and it is also an opportunity to replace both gaskets. I took them off together, ie: I did not disturb the fuel rail. Was a little tricky getting to 3 of the bolts inside the void but I have read reports of people otherwise having O ring leaks in the fuel rail when disturbed. 7) Upper manifold removal is not hard if you know what you are doing, I found some of the clips a bit tricky but if I were to do it again it would be a piece of cake.

I hope this is of use to you.

ps: You may want to consider having his job done.https://www.the75andztclub.co.uk/forum/showthread.php?t=182338 Perhaps you just get them to do the back cover while the upper manifold is off and you could do the front one.

Glad everything went according to plan.http://www.stillunfinished.com/wp-co...54cb9b2c59.jpg
http://www.youtube.com/watch?v=wyz_2DEah4o
It is well worth having a look at the inlet manifold gaskets in the picture. If you install new ones, I would seal with a bit of Victor Rinz's Rinzoseal. It is quite apparent that the bead of silicone applied from the gasket maker is insufficient, and will allow cooling water to penetrate from the cooling system and entering the cylinders (see the dark patches where water has penetrated the seals), causing water in the oil and exhaust. With time and further degradation, the problem will become intrusive.
If sealant is used, do so sparingly, nip the manifolds in place evenly, leave them to cure 24 hours, and then tighten and torque. That will leave a film of silicone as a firm substance and prevent the squeezing of silicone over the edges into oil, water and air ways.
After a week or two, you can expect the seals to have set, and a re-torque would be sensible.

Alf, I was going to let you know what clips I had used. I forgot! They were stainless steel genuine Jubilee clips, excellent quality, and I used three different sizes. I think I bought one pack of each size and that was about right, with a couple spare left over.

Definitely better than those rubbish OEM spring clips - of mine, either a fifth or a quarter of the total of the original clips had signs of having leaked at some point.