hi there i have a 120y coupe as a parts car for my sons 1200 coupe and want to swap mechacanicals over and need to know what changes are required to fit as engine mounts are different to 1200 also are the differentails compatible any feedback appreciated regards rocky

The differential in the 1200 is an H145 unit, which basicly means that it has a 145mm diameter crownwheel.
The differential in the 120Y will be an H150 unit [150mm diameter crownwheel]

The diferential from the 120Y will physicly fit into the axle housing of the 1200, however, the axle centerline is believed to be further back from the gasket face, so a spacer & a second gasket would be needed to space the H150 differential foward a little bit.

The problem is, no one seems to know for sure just how thick this spacer needs to be. Current theory sugests that the difference is 2.5mm, [half the difference in diameter between the crownwheels] which would need a 2mm spacer & a second gasket, which is .5mm according to my measurements.
The ratio for both differentials is 3.9 to 1.

As far as fitting the engine on the 1200 crossmember (as the engine mounts are in a different position). You can follow the instructions in this tecn section article link.

Tech Section - Engine

Have a sift throught the rest of that section, you might be able to answer a couple more questions that you haven't even thought to ask yet.

EDIT: This link is even better (still from the tech section) it gives actual plans of how to fit the engine mounts from a 120Y A12 into a 1200 body.

Tech Section - Engine better link

this parts car, was it the red one that sold for under $100 on ebay the other week? I knew I should have bought that one and dam the expenses!

sorry this one is teal blue brought on trademe nz

thanks for your help i have looked at the links you sugested but not to sure about height the motor will sit do you know if a 1200 ute x member will fitt as they run simm=ular engines and seem to have the same front end as dat 1200
any info appreciated regards rocky

if you get the later 1200 ute crossmember it will allow you to fit the 120y engine using the
120y engine brackets without any changes in suspension geometry or engine height.might be difficult to find one,as people rebuild these utes,not part them out.