Check transmission light / speedo failure

Desperately need help..

I`ve got a couple of problems I need alot of help with a 94 trooper bighorn 3.1TD Auto, uk spec RHD

1, The 'check transmission' light comes on after a few minutes then flashes all the time, I`ve read somewhere on this forum that I need to check the transmission fluid, I have no idea how to do this as there`s no dipstick,(apart from me) so can someone tell me how to do this and tell me where the fill plugs etc are located, bearing in mind that I am clueless as to the layout of the troopers bits and pieces so a diagram/pic would be great if possible.
Next problem is that the speedo stopped working (same time as check trans light came on)
Again I have seen a reference to a speed sensor but I have no idea where this is located (diagram would be a great help)
These two faults are obviously related, or are they ??

I will be eternally grateful to everyone that can help me with these problems as I have no idea whatsoever and don`t know where to start.

http://www.4x4wire.com/forums/postlist.php?Cat=&Board=UBB74

you might want to post your question to the above forum that deals with diesel Isuzu's.

good luck!