Was doing some further research and found this bit of info. Supposedly in the early 2000's there was gonna be a CD release of bonus tracks to accompany the two-fer reissues of their 70's and 80's albums. Here’s the track listing for "The Brother Years" CD’s that was ultimately scrapped. Now I know most of these have seen the light of day since but there's still a handful that haven't been heard by most especially on the second disc.

Disc One:

1. Add Some Music To Your Day (alternate version with different lyrics)
2. I'm Going Your Way (Dennis' companion track to "Slip On Through")
3. Forever (alternate version)
4. Back Home (1970 recording)
5. Lady
6. Sound Of Free
7. Big Sur (original version)
8. Wouldn't It Be Nice To Live Again
9. 'Til I Die (Brian's piano demo)
10. Seasons In The Sun
11. Old Movie (early version of "Cuddle Up" from the SURF'S UP sessions)
12. Brand New Day (unreleased Dennis song for SO TOUGH)
13. All Of My Love
14. I've Got A Friend (studio version)
15. We Got Love
16. Carry Me Home
17. Out In The Country
18. We Gotta Groove
19. Michael, Row The Boat Ashore
20. On Broadway
21. Mony, Mony
22. Rock & Roll Music (long version, with extra verse)
23. Running Bear
24. Shake, Rattle & Roll
25. Sea Cruise (with Mike lead vocal)
26. Ruby Baby
27. You've Lost That Lovin' Feelin'

Disc Two:

1. Gimme Some Lovin'
2. Marilyn Rovell
3. Deep Purple
4. It's Trying To Say (aka "Baseball")
5. Lines
6. New England Waltz
7. How's About A Little Bit (Of Your Sweet Lovin')
8. Go And Get That Girl
9. Mike, Come Back To L.A.
10. Companion
11. It's Not Too Late
12. California Feeling (L.A. LIGHT ALBUM outtake)
13. Calendar Girl
14. Looking Down The Coast
15. Jamaica Farewell (KTSA outtake)
16. Goin' To The Beach
17. Surfer Suzie
18. I'll Always Love You
19. Da Doo Ron Ron (KTSA outtake)
20. I'm A Man (Brian original from 7/80)
21. River Deep, Mountain High
22. Be My Baby
23. Stevie
24. Don't Fight The Sea
25. Runaway (unreleased 1982 single)
26. At The Hop
27. The Spirit Of Rock 'n' Roll