1976 buick electra vs. dodge rt4

It's not so much the transmission as the rear gear, my 69 Electra would go 0-55 in 1st, 55-90 in 2nd and I never had the guts to find out what it topped out at. One night coming back from picking my friend's 61 Electra (It had been in storage for the winter) we were on the highway and we decided to swap cars just to see what it felt like to drive a different Electra, a Porshe was passing me in John's 61 when I punched it and it dropped into 1st and I took off. This kinda shocked me as I was doing 65 at the time and I knew his car had a 2 speed transmission. Can't remember what speed I was going when it did shift into high, but I know that Porshe was just as shocked as I was.