Question: The Pontiac Sunfire shared a redesign with a line built on which platform?

Context paragraphs:
Pontiac Sunfire: The Pontiac Sunfire is an automobile that was introduced for the 1995 model year by Pontiac as the compact car to replace the Sunbird.  Not only was the name changed, but dramatic styling changes were included as well.  The new styling was shared with the redesigned Chevrolet Cavalier.  Along with the fresh new look the J platform was updated structurally to meet more stringent safety standards for the 1996 model year.

Siegfried Line: The original Siegfried Line (German: "Siegfriedstellung" ) was a First World War line of defensive forts and tank defences built by Germany in northern France during 1916–17 as a section of the Hindenburg Line.  In English the term "Siegfried Line" commonly refers to the "Westwall", the German term for a similar Second World War-era defensive line built further east during the 1930s opposite the French Maginot Line.  This line stretched more than 630 km and featured more than 18,000 bunkers, tunnels and tank traps.  The network of defensive structures stretched from Kleve on the border with the Netherlands, along the western border of the old German Empire, to the town of Weil am Rhein on the border to Switzerland.  It was planned in 1936 and built between 1938 and 1940.

Live from the House of Blues: Live from the House of Blues was a 26 part (one hour each) series on TBS that started airing in January 1995 at 12:05 AM Eastern Time on Friday nights and repeated at the same time on Saturday nights.  The timeslot was the same timeslot that another TBS music program, "Night Tracks" once occupied from 1983 to 1992.  It featured live music and was fronted by a rotation of celebrity hosts.  The show was produced by Michael Murphy Productions in conjunction with the "House of Blues" franchise.  The program ended its run about a year later.  It was sponsored by Pontiac and the Pontiac Sunfire.

Pontiac Sunbird: The Pontiac Sunbird is an automobile that was produced by Pontiac, initially as a subcompact for the 1976 to 1980 model years, and later as a compact for the 1982 to 1994 model years.  The Sunbird model ran for 18 years (with a lapse during the 1981 and 1982 model years, as the 1982 model was called J2000) and was then replaced in 1995 by the Pontiac Sunfire.  Through the years the Sunbird was available in notchback coupe, sedan, hatchback, station wagon, and convertible body styles.

Line 5 (Madrid Metro): Line 5 of the Madrid Metro originally opened between Callao and Carabanchel on 5 June 1968, the latter sharing station platforms with then called Line S (for "Suburbano") On 2 March 1970, the line was extended from Callao to Ciudad Lineal, however the section between Ventas and Ciudad Lineal was opened as part of line 2 in 1964.  In 1976, section of Line S Carabanchel - Aluche was transferred to the line in order to provide easier transfer to downtown to new railroad line to Alcorcón and Móstoles, now part of Cercanías C-5 line.  On 28 May 1980 the line was extended from Ciudad Lineal to Canillejas.  On the 27 October 1999, Eugenia de Montijo station was added between Aluche and Carabanchel.  The station is on the tunnel mouth of the line and is therefore overground.  The mostly overground section between Aluche and Casa de Campo was handed over to Line 5 after Line 10 was extended south from Casa de Campo on 22 May 2002.  On 24 November 2006, a two stop extension from Canillejas to Alameda de Osuna was opened.  A unique feature of Line 5 is that it carries the only above ground island platform at Aluche, and it is the only station were the metro is above the Cercanías, which is normally the other way round.  In the future, Line 5 is projected to be extended one stop north from Alameda de Osuna to Corralejos, where it will meet Line 8, however a new station will have to be built here to connect with line 5.  Line 5 uses 6-car trains of mainly class 2000B, however there are a few class 2000As running on the line.  It was the last line built in a narrow profile and gauge.

Chevrolet Cavalier: The Chevrolet Cavalier is a line of small family car automobiles produced for the model years 1982 through 2005 by Chevrolet.  Built on the General Motors J platform, the Cavalier achieved its highest sales in 1984.

San Lorenzo Zustinian class ship of the line: The "San Lorenzo Zustinian"-class were a class of at least twentynine 70-gun third rate ships of the line built by the Venetian Arsenale from 1691 to 1746, in three different series with minor changes in the ships' length.  It was the most numerous class of ship of the line built in Venice, and the last to see active service in a war against the Ottoman Empire in 1718.  All this class' ships were planned before 1720, and the vast majority was launched before the Peace of Passarowitz.  The last four vessels were completed to a 70% in 1720s, then stored in the roofed shipbuilding docks of the Arsenale to be finished and launched between 1739 and 1746, a solution that was widely used with the following "Leon Trionfante"-class.

Graham Line: The Graham Line (also known as the Guymard Cutoff) is the portion of the former Erie Railroad in New York State from Highland Mills (at about ) to Guymard (at about ), built in 1904–1908 as a low-grade freight line.  The Graham Line bypasses the original Erie Main Line through Monroe, Chester, Goshen and Middletown.  Grade on the Graham Line was not to exceed 0.2% eastward or 0.6% westward, while the original Main Line built in the 1840s had grades up to 1.25%.  There were three places where freight trains needed a helper on the old line and none on the new, but just west of the cutoff the grade up from Port Jervis to Guymard could not be improved and remained unchanged as the only place in the area needing a helper.  The sharpest curve on the old line was 7 degrees and on the new was 1 deg 30 min.  The Graham Line has no grade crossings, a rarity on the Erie.  The downside of the improved grade and curvature is that the Graham Line is seven miles longer.  Maintaining the desired grade required two notable engineering features, the Moodna Viaduct and the Otisville Tunnel.

Line 1 (São Paulo Metro): Line 1 (Blue) was the first line built for the São Paulo Metro.  It links Tucuruvi Station to Jabaquara Station.  Construction began in the late 1960s and was completed in the early 1970s.  It was also the first metro line built in Brazil.

Alamosa–Durango Line: The Alamosa–Durango Line or San Juan Line was a railroad line built by the Denver and Rio Grande Western Railroad, following the border between the U.S. states of Colorado and New Mexico, in the Rocky Mountains.  The line was originally built as a narrow-gauge line between its namesake cities of Alamosa and Durango.  However, through the years portions of the line were re-gauged multiple times and both narrow-gauge and extensions and branches were built.  Three portions of this line survive today: the now standard-gauge portion from Alamosa to Antonito, Colorado, and two narrow-gauge portions operated as heritage railways.

Supporting paragraphs: Pontiac Sunfire Chevrolet Cavalier
Answer: General Motors J