Hi, I own a K51 Deluxe and a K52 Manhattan, both export cars from US. The K51 is running since 1987 very well where the K52 is still in restoration. 10 years ago I installed hardened outlet valves and seats on the K51 to use leadfree fuel and it works just fine. Now there is a very disturbing motor oil leak occuring at the rear seal (obviously a very known problem). I got the engine out, separated the Hydramatic shifting and took the oilpan off, then the Crankshaft rear filler block. Now, to replace the lower half oil seal is easy, but how to replace the upper half? The guard holding the seal is installed tight beneath the crankshaft. Do I need to take the whole crankshaft off (I prefer not to), or is there a way to push/pull out the old seal and push in the new seal? I doubt that this would work. Who of you people has experience in doing this? Thanks for any remarks on this issue.