Thanks for you info guys
Useful
Still a bit confused .I have the LMC catalogue . According to their drawings I have the front suspension detail of the 1st series 1/2 ton , but the rear suspension detail of the 3/4 ton. The main difference appears to be the rubber bump stop position
.
Any way , i have now located a 3/4 ton chassis just 10 miles form me here in england and so intend to swap the 3 leaf springs for the proper 7 leaf set and fit its shocks as well .Will be binning the air shocks!