Detroit acquired defensive tackle Dave Gallagher and fullback…

Contemporary reporting and Detroit's later transaction history support treating this as a two-player, two-pick exchange, while also explaining a small date discrepancy in later ledgers. An Associated Press report published August 3, 1978 said Detroit had announced the acquisition of Dave Gallagher and Marsh White from the Giants for two undisclosed future draft choices. Detroit's historical transaction ledger later lists Gallagher as acquired on August 2 for a 1979 eighth-round pick and White as acquired on August 7 for a 1979 eleventh-round pick. Pro Sports Transactions maps those choices to No. 201 Roy Simmons and No. 284 Ken Johnson. TradeVerdicts retains August 2 as the package announcement date but records the later ledger's separate processing dates in QA rather than inventing additional consideration.

Gallagher gave Detroit the only regular-season production from the two incoming players. NFL records show him appearing in one game for the Lions in 1978 and 10 games with seven starts in 1979, for 11 Detroit games and seven starts overall. Pro Football Archives also credits him with 1.5 sacks across those two seasons. Gallagher retired after 1979. That is real defensive-line service, but it amounts to less than one full season of appearances across the two-year span.

White never appeared in a regular-season game for Detroit. NFL's career record lists only his 1975 and 1976 Giants seasons, when he played 28 games and rushed for 313 yards. Contemporary reporting noted that injuries had interrupted his career before the Lions acquired him. Because no Detroit regular-season appearance followed the trade, his prior Giants production cannot be transferred to Detroit's side of the evaluation.

New York turned the eighth-round pick into Simmons, who became the most valuable asset in the deal. The Giants' 1979 media guide identifies Simmons as their second eighth-round selection and later club records identify that choice as coming from Detroit. Simmons played every game for New York from 1979 through 1981, totaling 48 regular-season appearances and 29 starts. He started all 16 games at guard in 1980 and 10 more in 1981. That is strong multi-year offensive-line value from a late-round pick.

The eleventh-round pick also produced immediate contribution. The Giants' 1979 media guide explicitly identifies Johnson as their second eleventh-round selection via Detroit. NFL records show him playing nine games for New York in 1979, starting seven, rushing 62 times for 168 yards and catching 16 passes for 108 yards and one touchdown. His career lasted only that season, but the combined return of Simmons and Johnson clearly exceeds Detroit's 11 games from Gallagher and zero from White. A B+ for the Giants and C+ for the Lions reflects New York's durable starting-line value without overstating the late-round package as a franchise-changing return.