Tune up

1999 Isuzu Trooper 112.000 milles, TOD, new transmission.

I'm getting ready to do tune up and change most of the fluids
How and what do i use to change: front and rear axel, TOD, shift on the fly?
transfer case fluids.
I'm planning on installing BOSH +4 spark plugs, what do you think?

For transmission fluid should i put syntetic or stick with normal oil?
Any additives?

I know you supposed to put some aditive in to axle oil do i have to use the one that is being suggested by manual or any limited slip differential will work?
One more thing, when in drive and i step one the gas it sounds like an exaust leak but not when parked.

I'll save you some major trouble, don't buy Bosch +4 plugs. Many have reported that these plugs cause the CEL to toss miss fire codes.

you exhaust leak could be your intake manifold gasket sucking air.

Read up on the FAQ's for helpfull hints.