Looking for trailing arms and left window reg?

[68haywagon]

Hello,
I am new to the forums here and a new truck owner. I just purchased a 1968 C-10 2wd lwb pickup. Got a good deal on the truck but need a set of trailing arms to "safely" drive it. The left arm you can see the other half through and and the right one is not much better. I am kind of on a limited budget right now and any help finding these will be appreciated. Also the left window is playing auto down. Is this the regulator that is bad? If so any of those out there?

Also does anyone know the correct tires size for these trucks. All the tires are just about bad and they are all different sizes. The rims are 15" 6 lugs.

Thanks,
Mike