Hello, my name is vDraxx.
Today I will show you the best seed on Tekkit (I think it only works on Tekkit, not on other modpacks).
Seed: -304941192843830851
Longest cave mine in Tekkit (probably even in Minecraft!):
X: 324
Y: 69
Z: 231
I will show you 3 ravines. 2 normal ravines and 1 small ravine.
Small ravine:
X: 324
Y: 64
Z: 291
Normal ravine 1:
X: 313
Y: 63
Z: 297
Normal ravine 2:
X: 213
Y: 64
Z: 275
These are the only ones I know from my 3 in-game days of Tekkit. Reply if you found anymore.