Try here http://www.motomobil.com/escort-u-orion,2409.html
A friend of mine purchased a saph chassis rail about 2 yeaRS ago and was decent money .
Once your on the link click 'spare parts'..... Then goto download price lists (html) scroll down to Escort 4 or 3 open the file and go to body/diverse . They list certain chassis parts by the looks of it not sure if its what your after though .

hth