Windscreen

Hi all
Will the one piece windscreen from the defender fit my series 3 bulkhead to replace the split screen.
The car has a range rover chassis shortened to 88 inch, coil springs and discs all round. It has the 2.5td engine with a LT77 gearbox that is about knackered. Would the R380 fit as a straight replacement?
Butty

if you have hard top it will need changing as well,disco rr boxes lt77 and r380 are the same dimensionally def ones arent