Piper Service Bulletin number 1160 specifies two corrosion inhibitor products for “all other reworked items”, whatever that means. It does not specify a product for the torque tube other than “2 swab coats of epoxy primer” to the interior. After the epoxy primer I suggest applying one of those specified or CorrosionX® [red can for steel components, blue can for aluminum] heavily to the inside of the torque tube before installation and lightly to the outside of the torque tube before further assembly [of the stabilators].
SB-1160 further states in part 2, 1; “… repair per chapter 6 of FAA document AC43 13-1B …”. Section 6 is corrosion removal [6-116] and plating [6-164].
I would also suggest further disassembly to check for cracking of the horn [future AD] and write the log book entry in hopes this work, if performed prior to the AD, will CYA. I also perform the unapproved procedure of chamfer and polish the bores’ intersection, plus dye penetrate or eddy current inspect, glass bead blast, clean, Alodine® and epoxy prime the aluminum components. I use an external stamped mark [a circled “M”] to indicate the procedure; see the photos elsewhere.
The aluminum components of the torque tube assembly as well as the inside of the torque tube have been painted using Sherwin Williams® Aerospace Coating Epoxy Primer MIL-P-23377F after proper preparation as mentioned above. The exterior of the balance tube and weight have been likewise painted using the MIL-P and Sherwin Williams® Acry Glo® white. You’ll notice there is minimal paint film thickness on the bearing blocks; an important detail. Paint-film thickness can be a source of fretting corrosion where the blocks attach to the aft bulkhead. If you choose to refinish the bulkhead please be aware of this detail; use only a thin coat of epoxy primer. Reference AC 43.13.1B, see section 6-22, fretting corrosion.
For another interesting read, go to AC 43.13.1B, see section 6-20. Therein is described one suggested [partial] failure mechanism for the cracking issue, stress corrosion cracking.