series 4 and 5 gearbox brackets are different. series 4/5 box are pretty strong. a series 1 box wont last long if u drive it hard.

as for the 12a timing cover. get a rotor shop to do it because there is some seals you can damage in the changeover. the thing is you need to change ur sump then to an rx4 sump if you go `12a timing cover.

i think the mad dat kit is a good way to go. saves you buying a 12a timing cover, sump and getting someone to change the front cover over. then you have to make engine mounts and bracketts.

datto 13b i pm'd you my number. if you give me a call il give you the run down

if i was to fit another 13b to a 1200 id use the mad dat kit.