Differential washer woes

After some very useful pointers, i have had a look around and given everything a good shake. Two finds:

  1. Gap at diff body to chassis is easily 20mm (lowest pointy) as i can wiggle my fat finger in it with ease - Can someone tell me the bolt type/length, and sizes of thick/small washers as it obviously needs to be lowered. So I can go shopping at local bolt store tomorrow.
  2. On gentle rolling wheels back and forth i have found a clicking that repeats at same point. With a little more gusto the clicking gets a little louder. i suspect its either new UJ axles or prop shaft, perhaps emanating from diff that’s hanging to high. On slow speed turning does this become my loud rotational knock.
    Thoughts appreciated.

I found the washers were simple shock absorber washers that were placed on both sides (4 washers total) of each rubber bushing.