The widths vary between brands.  Just make sure that there is no groove worn on to the sealing area of the crankshaft.  The seal does not have to be worn out to cause a wear groove.  I just did a repair sleeve on a rear end pinion shaft.  Big wide wear groove, not the typical thin seal spring wear.

Oops, forgot a link -

https://www.rockauto.com/en/catalog/nissan,1977,280z,2.8l+l6,1209248,engine,crankshaft+seal,5604

Edited March 1Mar 1 by Zed Head

Sorry for the delay. The transmission is in, without to much drama. Installed my new Z Story exhaust (Street Sport Header) That went well. Thanks for the tips from @Patcon

But now to the what was I thinking catagory☹️ Went to install my heat shield and it is not going to clear the new header. Should of new that from the start.

So what are my options? No heat shield? If so what do you attach the return spprings to? Does anyone make a shield that will work? (running SU's)

Any ideas would be welcomed. Patcon are you going to run SU's? If so do you have a plan?

Thanks for the help.

Stee

Did you have the headers Ceramic coated? I understand that’s not the issue at hand but will eliminate carb problems.

I did not. Was going to wait and see if there was going to be a problem with the heat.