T400 questions (horse isn't quite dead yet)

[Luvlegs]

I have the original 454/400 that was pulled from a 73 ElCamino SS - the tranny needs to be rebuilt so it'll be a while before I actually get around to installing it.

Question 1 - What/Is there a difference between a T400, TH400, etc or are
they all the same thing? (I keep seeing them called several
different names)

Question 2 -A I have been told it doesn't have overdrive (ok..) but I keep
seeing "kick down" this and "kick down" that, related
400s.... what am I missing, is that just a drop down in gears to
pass thing?
B I had a 400 tranny behind a 400 in a 67 pontiac - I dont
remember anything connected to it but the speedo..... am I
missing something? The car was killer and I didn't notice
anything possibly wrong....

Question 3 - What are all the parts related to the linkage for the 400 on our
trucks? Rod, frame bracket, ??? Anyone have any pics of all of
them together?

Question 4 - What are all the parts/linkages related to install the kickdown
(or do I even need it?) and again, does anyone have pics of
them all together?
Thanks all!