[Vwdiesel] What's the difference between FF and FN trannys?

[VintagePkr at aol.com]

Hi,
I mentioned last week that my 85 golf blew a hole in its 5 speed tranny and I
have a 81 pickup with a 5 speed which I was going to swap into it.  Well, it
seems that mecanically it will be a pretty straight swap but I want to know
if there is a major difference in the tranny's performance.   For instance,
My Golf had noticeably more robust acceleration and higher to speed than the
pickup did yet they were both 1.6 and almost identical weight.
So I was wondering...
Did the pickup come with a "torquey-er" transmission that the pasenger cars?
Is that the difference between the FF and FN trannys?
Are there any others?
I do a lot of highway driving with this Golf and I would rather have the top
speed rather than the pulling power.  (the Golf would cruise happily at 70mph
while the pickup at 70 felt like it was turning a bit too fast for its liking)
Which tranny would you folks suggest for this application?
I dont have the funds to have one custom built or re-geared I just want to
know which tranny code to have in mind when I search the used part sites and
junkyards.
TIA
Keith