Slide assembly

[Mitchzilla]

im looking into buying a slide assmelby for my mossberg 500 because my forend its just one piece. I see on brownells that they have them but they are 2 different sizes ones 6.75" and ones 7.75" which one would i need.

 

[Greenhorse six]

I think newer guns use the longer one, both will work, are you getting a new forend as well or going with the one you have? just measure the one you have ,that'll be the size to get.