factory 100mph speedo into 87 gmc

[lay low 87]

ive heard of this a while back and recently i was considering doing it since ive gotta replace the vehicle speed sensor and speedo cable anyway. did some searching but came up with nothin.

is this a bolt in mod? will it interfere with my ECM at all?

[iceman7329]

there is no VSS on that truck as it has a cable driven speedo so it wont mess with the ECM

[lay low 87]

so i guess ill lose my TCC lockup in 4th?

[iceman7329]

I dont know about that, I didnt know you had a 700R4.