were to find flack guns

I think Bandaii makes a Flak 88.

i saw a 1/48 88 flak and some kind of 1/48 flak trailer
(not sure what that means, there was no picture)
on www.greatmodels.com

You say FLAK so I assume you mean Jerry.

North Star makes two light AAA models in 1/48th.
http://www.northstarfigures.com/shop/resinvehicles/

Tarmac does too:
http://www.parabellum.co.uk/prc3.htm

Fuman makes the 88:
http://www.parabellum.co.uk/prc1.htm

I think Tamyia also makes makes a Flak 88 in 1/35, and I know that they make at least two diffrent flack adaptions for the panzer IV (morbelwagon and Flakpanzer) and one on a half track too, all in 1/35,I think.
Hope that helps!

on the 1/48 front go to
http://www.track48.com/index.html
and take a look at the links pages.
there may be a lead there.

good luck.