Hi,
...I've had similar prob with mine, plenty of 2nd hand shit for stupid money...I got lucky with a b king shock for £7 (plus postage). They are about 10mm shorter than standard so I've fashioned a bracket that bolts on to the frame just above the existing shock mount, 10mm lower than stock. There was a bit of shaving off to do on the bottom swivel mount but it fits well. Only downside is that I've had to mount a smaller battery where the tool kit used to be.