Moshin Amin had been found guilty of conspiring to possess a firearm with intent to endanger life with Yassar Yaqub.
Mr Yaub was the front seat passenger in one of two cars travelling in convoy when four unmarked police vehicles surrounded them at junction 24 of the motorway at Ainley Top, Huddersfield.
He was shot at 6.05pm on January 2 last year after an undercover police operation in which officers from West Yorkshire had been deployed to observe individuals including Mr Yakub.
Amin, 32, of Broomer Street, Dewsbury, was arrested at the scene along with two others.
Following a two-week trial, he was convicted of conspiracy to possess firearms with intent to endanger life.
The court heard how police recovered a loaded handgun from the footwell and a silencer and further ammunition from the glovebox of the vehicle being driven by him.
David Butlin, 39, of Upper Sunny Bank Mews, in Meltham, was found guilty of possessing a dagger, which police found hidden down his shorts.
A third man, Rexhino Arapaj, was acquitted by the jury at Leeds Crown Court.
Today, a judge sentenced Amin to 18 years in prison and Butlin to 18 months in prison.
Detective Chief Superintendent Nick Wallen, from West Yorkshire Police`s Major Enquiry Team, said: “We are extremely pleased with the findings of guilt and with the sentences which have been handed down today to these dangerous individuals who were involved in serious and organised crime.
“There is currently an ongoing investigation being undertaken by the Independent Office for Police Conduct (IOPC) and also a forthcoming inquest into the death of Mr Yaqub and therefore we will not be able to provide any further comment at this time.”
Gerry Wareham, Chief Crown Prosecutor for Yorkshire and Humberside, said: “The jury found that Moshin Amin was a party to an agreement with Yasser Yaqub to possess the gun, silencer and ammunition for the purpose of endangering the lives of others. We were able to provide evidence to show that the background to this was an ongoing drug feud.
“Moshin Amin also had with him mobile telephones equipped with ‘stealth SIMS’ so as to hide the identities of those using them and the calls made. David Butlin also accepted he had used a phone equipped with a stealth SIM.
“Today Moshin Amin will begin serving a lengthy prison sentence as a result of his involvement in organised criminality.”