Well...strictly speaking there is probably a "torque spec" for every engine/tranny fitting but, in reality, the most important thing is that the bolts be tightened in the proper sequence and they all be at approximately the same tightness. IOW, the actual torque setting for other than critical fasteners (main/rod/head bolts, etc) is not that important. But generally fasteners for a component should be tightened inside to outside and in alternating order. This ensures that the mating surfaces stay true to each other. Basically, you never tighten fittings by going from one bolt to the next. That's a good way to warp the surfaces.
There are a ton of explanations on line and in any service manual for the particular engine/transmission tightening sequence/torque.
Torque wrenches are valuable for critical fasteners but one must also be aware of the specs for the particular assembly - is the torque spec for lubed fasteners or dry; if lubed, what lube? The traditional spec for lubed auto engine bolts is using sae 30 motor oil. But some manufacturer service manuals state dry/clean as opposed to clean/lubed. The difference in actual bolt stretch between dry and lubed can be 30% or more. IOW, if a fitting is spec'ed as dry and you lube it, the torque spec could cause the fitting to break.
The old story re torque settings is that some company had their best mechanic assemble an engine and then published the torque based on how he tightened the relevant bolts...
A lot of people use anti-sieze routinely with absolutely no regard for the change in the torque spec that should be incorporated if the original spec was for dry.
I just looked up the torque settings for a grade 5 steel bolt in steel/cast iron - 40LbFt; in AL it's 30. That setting is dry/clean. If you lube the clean bolt, the torque setting in both cases is reduced by approx 20%
